Villanelle sits in a window seat in the south wing of the Louvre art gallery in Paris. She is wearing a black cashmere sweater, leather skirt, and low-heeled boots. Winter sunshine pours through the vaulted window, illuminating the white marble statue in front of her. Life-sized, and entitled Psyche Revived by Cupid's Kiss, it was carved by the Italian sculptor Antonio Canova in the final years of the eighteenth century.

It's a beautiful thing. Psyche, awakening, reaches upwards to her winged lover, her arms framing her face. Cupid, meanwhile, tenderly supports her head and breast. Every gesture speaks of love. But to Villanelle, who has been watching the visitors come and go for an hour now, Canova's creation suggests darker possibilities. Is Cupid luring Psyche into a sense of false security so that he can rape her? Or is it Psyche that's sexually manipulating him, by pretending to be passive and feminine?

Unaccountably, passers-by seem to take the sculpture at its romantic face value. A young couple imitate the pose, laughing. Villanelle watches closely, notes how the girl's gaze softens, how the flutter of her eyelashes slows, how her smile turns to a shy parting of the lips. Turning the sequence over in her mind like a phrase in a foreign language, Villanelle files it away for future use. Over the course of her twenty-six-year lifespan she has acquired a vast repertoire of such expressions. Tenderness, sympathy, distress, guilt, shock, sadness… Villanelle has never actually experienced any such emotions, but she can simulate them all.

"Darling! There you are."

Villanelle looks up. It's Anne-Laure Mercier. Late as usual, with wide apologetic grin. Villanelle smiles, they air-kiss, and stroll towards the Café Mollien on the gallery's first-floor landing. "I've got a secret to tell you," Anne-Laure confides. "And you mustn't tell a soul."

Anne-Laure is the closest thing that Villanelle has to a friend. They met, rather absurdly, at the hairdresser. Anne-Laure is pretty, extroverted and more than a little lonely, having exchanged life at a busy public relations firm for marriage to a wealthy man sixteen years her senior. Gilles Mercier is a senior functionary at the Treasury. He works inordinately long hours, and his greatest passions are his wine cellar and his small but important collection of nineteenth-century ormolu clocks.

But Anne-Laure wants to have fun, a commodity sadly lacking in the life she shares with Gilles and his clocks. Right now, before they've even reached the curving stone staircase up to the restaurant, she's pouring out the details of her latest affair, with a nineteen-year-old Brazilian dancer at the Paradis Latin cabaret.

"Just be careful," Villanelle warns her. "You have a lot to lose. And most of your so-called friends would go straight to Gilles if they thought you were playing around."

"You're right, they would." Anne-Laure sighs, and links her arm through Villanelle's. "You're so sweet, you know that? You never judge me, and you're always so concerned."

In truth, it suits Villanelle's purposes to spend time with Anne-Laure. She's well-connected, with an insider's access to the finer things of life. Haute couture shows, tables at the best restaurants, membership of the best clubs. Besides which she's undemanding company, and two women together attract far less attention than a woman on her own. On the negative side Anne-Laure is sexually reckless, and it can only be a matter of time before some indiscretion is brought to Gilles's attention. When that happens, Villanelle doesn't want to give the impression that she's complicit in his wife's infidelity. The last thing she needs is the hostile attention of a senior public servant.

Villanelle squeezes the other woman's arm. "I care about you. I don't want to see you hurt."

As they eat, and Anne-Laure talks about her new amour, Villanelle makes attentive noises. But her mind is elsewhere. Fine-living and designer clothes are all very well, but it's months now since the Palermo operation, and she badly needs to feel her heart race with the prospect of action. More than that, she wants confirmation that she's valued, that the organisation regards her as a prime asset.

"So how come you're not shorting the Nikkei Share Index or whatever it is that day-traders do?" Anne-Laure asks, when they are finally installed at a table.

Villanelle smiles. "Even super-capitalists need a day off. Besides, I wanted to hear about this new guy of yours." She looks around her at the shining silver and glassware, the flowers, the paintings, the golden wash of the lights. Outside, beyond the tall windows, the sky has faded to a snow-laden grey, and the Carousel Gardens are almost deserted.

She can still see, half a world away, the grim sprawl of the Dobryanka remand centre. Was it worth it? Konstantin had asked her. Throwing her life away to avenge her father, himself a man who'd gone to the bad. Put like that, of course, it wasn't worth it. But given her time again, she knew that she'd act exactly as she'd acted that night.

There hadn't been many birthday or New Year presents, but her father had taught her to defend herself, and more. There had been memorable days in the forest, wrestling in the snow, shooting at tin cans with his old Makarov service pistol, and lopping through birch-trunks with his Spetsnaz-issue machete. She'd hated the machete at first, finding it heavy and unwieldy, but he'd taught her how it was all in the timing. That if you got it right, the weight of the blade and the arc of the swing did the job for you.

She'd found out easily enough who killed him. Everyone knew; that was the point. Boris had tried, clumsily, to defraud the Brothers, and they'd shot him and left his body in the street. The following evening Oxana walked into the Pony Club on Ulitsa Pushkina. The three men she was looking for were standing near the bar, drinking and laughing, and when she sauntered up to them, smiling suggestively, they fell silent. In her army-surplus jacket and supermarket jeans she didn't look much like a shlyukha, a whore, but she was certainly acting like one.

Her father had been a close-quarter battle instructor before he'd started freelancing for the Brothers' Circle. And although Boris Vorontsov hadn't been the ideal parent, given to whoring and heavy drinking, and dumping Oxana in the orphanage whenever he went away on active service, he was her flesh and blood, and all she had after her mother's death.

Oxana stood there for a moment in front of them, looking from face to face with taunting, amused eyes. Then she dropped into a crouch, her arms reaching back between her shoulder blades for the machete in its webbing holster, and drove upwards through her knees as her father had taught her. Half a kilo of titanium-finished steel blurred the air, the chisel-edge passing unchecked through the first man's throat before burying itself deep below the second man's ear. The third man's hand dived to his waistband, but too late: Oxana had already let go of the machete and drawn the Makarov. Around her, she was vaguely aware of panicked breathing, suppressed screams, people backing away.

She shot him through the open mouth. The report was deafening in the enclosed space, and for a moment he just stood there staring at her, blood and brain-matter spilling from a gaping white flap of bone at the back of his head. Then his legs went, and he hit the floor beside the first man, who was somehow still on his knees, a desperate, dregs-of-the-milkshake rasp issuing from the bubbling gash beneath his chin. The third man wasn't finished yet, either. Instead, he was lying in a foetal position in the spreading red lake, his feet working feebly and his fingers plucking at the machete embedded in the angle of his jaw.

"Chérie!"

"Honestly, sweetie, sometimes I wonder where you go in these daydreams of yours. Are you seeing someone you haven't told me about?"

Oxana watched them, annoyed at their failure to die. It was the kneeling man who really infuriated her, making that sick, Strawberry McFlurry noise. So she knelt beside him, drenching her Kosmo jeans in blood. His gaze was failing, but the eyes still held a question. "I'm his daughter, you cunt," she whispered and, pressing the Makarov's barrel to the nape of his neck, squeezed the trigger. Again, the detonation was appallingly loud, and the man's brains went everywhere, but the sucking noise stopped.

"I'd better be. You can be so mysterious at times. You should come out with me more often, and I don't mean shopping or fashion shows. I mean…" She draws a fingertip down the frosted stem of her champagne flute. "More fun stuff. We could go to Le Zéro Zéro or L'Inconnu. Meet some new people."

She blinks. The restaurant swims back into focus. "Sorry, I was miles away… What did you say?"

Villanelle smiles at the waiter hovering patiently at her side. "Small espresso, thank you."

"Coffee?"

"No. Don't worry, you'd be the first to know."

"You're so boring."

"I have to go. Work."

In her bag, Villanelle's phone buzzes. A single word text-message: CONNECT.

"I know. Sorry."

"Oh, please, Vivi, you're impossible. You haven't even had your coffee."

Two hours later Villanelle is sitting in the study of her rooftop apartment in the Porte de Passy. Beyond the plate-glass window the sky is cold steel.

The email contains a few lines of text about skiing conditions in Val-d'Isère, and half-a-dozen JPEG images of the resort are attached. Villanelle extracts the password and accesses the payload of compressed data embedded in the images. It is a face, shot from different angles. A face she memorises like the text. The face of her new target.

"I'll do without."

Thames House, the headquarters of the British security service MI5, is on Millbank, in Westminster. In the northernmost office on the third floor, Eve Polastri is looking down at Lambeth Bridge and the wind-blurred surface of the river. It's 4 p. m. and she has just learnt, with mixed feelings, that she is not pregnant.

Eve takes off her reading glasses and rubs her eyes. Wise eyes, her husband Niko calls them, although she's only twenty-nine, and he's almost ten years older. She and Simon have been working together for a little over two months. Their department, known as P3, is a subsection of the Joint Services Analysis Group, and its function is to assess the threat to "high-risk" individuals visiting the UK, and if necessary to liaise with the Metropolitan Police with a view to providing specialist protection.

At the next terminal, her deputy Simon Mortimer replaces his teacup in its saucer. "Next week's list," he says. "Shall we run through it?"

It's in many ways a thankless task, as the Met's resources are not infinite, and specialist protection is expensive. But the consequences of a poor judgement call are catastrophic. As her former head of section Bill Tregaron once said to her, before his career went into freefall: "If you think a live extremist preacher's a headache, wait until you have to deal with a dead one."

"How seriously we should take him. I mean, we can't ask the Met to babysit every crackpot political theorist who shows up at Heathrow."

Eve nods. With her make-up-free complexion and nondescript brown hair gathered in a scrappy up-do, she looks like someone for whom there are more important things than being thought pretty. She might be an academic, or an assistant in the better sort of bookshop. But there's something about her -- a stillness, a fixity of gaze -- that tells another story. Her colleagues know Eve Polastri as a hunter, a woman who will not readily let go.

"Go on."

"Tell me," Eve says to Simon.

"The Pakistani writer, Nasreen Jilani. She's speaking at the Oxford Union on Thursday week. She's had death threats."

"So who requested protection for Kedrin?" she asks.

"Then there's the Russian, Kedrin. I'm not so sure about him."

"Reza Mokri, the Iranian nuclear physicist. Again, full protection."

"What aren't you sure about?"

"Plausible enough. SO1 have agreed to put a team on her."

"Agreed."

"Plausible?"

"And Viktor Kedrin's their poster boy."

"Then you'll know what I mean. They look more cranky than dangerous. All this stuff about the mystical bonds between Europe and Russia, and how they should unite against the corrupt, expansionist USA."

"Yes, at somewhere called The Vernon."

"He's the ideologist. The face of the movement. Charismatic figure, apparently."

"But not at immediate risk in London, surely?"

"Eurasia UK, the group which organised his visit. I've run checks, and they're --"

"Is that where he's going to be staying?"

"I know who they are."

"Maybe, maybe not."

"I know. It's pretty wild. But they've got no shortage of supporters. Including in the Kremlin."

"I mean, who would he be at risk from? The Americans aren't crazy about him, obviously, but they're not going to call in a drone strike on High Holborn."

Eve nods. "I suppose you're right. We don't need to trouble Protection Command with Mr. Kedrin. But I think I might go to his talk -- I assume he's addressing the Eurasia UK faithful at some point?"

Keying in her identification code, Eve calls up the HST, or High Security Threat list. Circulating among friendly intelligence services, including on-off allies like the Russian FSB and the Pakistani CID, this is a database of known international contract killers. Not local enforcers or fly-in-fly-out shooters, but top-echelon assassins with political clients and price tags affordable only by the seriously wealthy. Some of the entries are lengthy and detailed, others are no more than a code name harvested in the course of surveillance or interrogation.

"Good. Keep me posted."

"The Conway Hall. Friday week."

Simon inclines his head in assent. Although only in his twenties, he has the arch solemnity of a metropolitan vicar.

For over two years now Eve has been building up her own file of unattributed killings of prominent figures. A case she constantly returns to is that of Dragan Horvat, a Balkan politician. Horvat was an exceptionally nasty piece of work, implicated in human trafficking and much else besides, but that didn't save Bill Tregaron when Horvat was murdered in Central London on his watch. Relieved of his post, Bill was seconded to GCHQ, the government listening centre at Cheltenham, and Eve, previously his deputy, became head of section at P3.

Horvat was killed on a trip to London with his girlfriend, a seventeen-year-old heroin addict from Tblisi named Irema Beridze. Officially, he was in London as a member of a high-ranking trade delegation; in truth, he and Irema spent most of their time shopping. They had just left a Japanese restaurant in a poorly lit side street in Bayswater when a hurrying figure bumped hard into Horvat, almost knocking him down.

In a cheerful mood, well lubricated by sake, Horvat was initially unaware that he had been stabbed. Indeed, he apologised to the disappearing figure before becoming aware of the warm blood pumping from his groin. Open-mouthed with shock, he sunk to the pavement, one hand clamped uselessly to his severed femoral artery. It took him less than two minutes to die.

Irema was still standing there, shivering and uncomprehending, when a party of Japanese businessmen left the restaurant a quarter of an hour later. Their English was imperfect, hers non-existent, and it was a further ten minutes before anyone called the emergency services. Irema was profoundly traumatised, and initially insisted that she could remember nothing about the attack. But patient questioning by an officer from the Metropolitan Police's SO15 Branch, assisted by a Georgian interpreter, eventually elicited a single key fact. Dragan Horvat's killer was a woman.

Neither could have killed Horvat, for the simple reason that by the time the politician met his end in London both were dead. Golovkina had been found hanged in a hotel wardrobe in Brighton Beach more than a year earlier, and Markovic had predeceased her by four months, blown to shreds by a car bomb in Belgrade. So if Irema Beridze was right, it meant that there was a new female assassin abroad. And this interests Eve very much indeed.

Professional female assassins are very rare indeed, and since joining the Service Eve has been aware of just two. For some years, according to the HST file, the FSB used a woman named Maria Golovkina to execute overseas hits. A member of Russia's small-bore pistol squad at the Athens Olympics, Golovkina is thought to have been trained in covert assassination at the Spetsnaz base in Krasnodar. There's also an entry in the file for a Serbian hitwoman, attached to the notorious Zemun clan, named Jelena Markovic.

Why, she isn't completely sure. Perhaps because she can't imagine taking a human life herself, she is fascinated by the notion of a woman for whom killing is unexceptional. Someone who could get up in the morning, make coffee, choose what to wear, and then go out and cold-bloodedly put a total stranger to death. Did you have to be some kind of anomalous, psychopathic freak to do that? Did you have to be born that way? Or could any woman, correctly programmed, be turned into a professional executioner?

Since taking over P3 from Bill, Eve has conducted a discreet but exhaustive search of the live case files for any further suggestion of female involvement in an assassination, and has flagged two references. The first involves the shooting in Germany of Aleksandr Simonov, a Russian business oligarch suspected of funding Chechen and Dagestani militants as part of a deal relating to oil and gas concessions. The assassin, who fired a burst of six rounds from an FN P90 sub-machine gun into Simonov's chest outside the Frankfurt headquarters of the AltInvest Bank, was wearing despatch-riders' waterproofs and a full-face motorcycle helmet, and raced away on a machine later identified as a BMW G650Xmoto. Of the dozen or so onlookers questioned afterwards, two stated that they "had the impression" that the shooter was a woman.

The other case, the close-up slaying in Sicily of a Mafia boss named Salvatore Greco, is apparently non-political. Local innuendo attributes the slaying, directly or indirectly, to the dead man's nephew, Leoluca Messina, who has since assumed the leadership of the Greco clan. But there has also been speculation in the press about an accomplice, the so-called "woman in the red dress." According to the investigators of the DIA, the Direzione Investigativa Antimafia, Greco was found dead in a private box at the Teatro Massimo in Palermo, following an opera performance. He had been shot in the heart at close range with two low-velocity.22 rounds. His two bodyguards were also found dead on the floor of the box, despatched with single shots to the base of the skull.

Which, Eve reflects, is certainly no accident. The woman is well aware that the CCTV camera is there. But the really strange detail is one that the DIA have not made public. Before Greco was killed, he was immobilised with a lethal tranquilliser apparently delivered via a custom-made device that was found buried in his left eye. A photograph of this device is in the online case-file, along with details of its inner workings. It's a sinister-looking thing: a curved and hollowed steel spike containing an inner reservoir and armed with a tiny plunger.

Leoluca Messina is known to have been at the theatre that night, and a witness has described seeing him in the bar shortly before curtain-up, talking to a striking dark-haired woman in a red dress. It appears that they were not sitting together, but CCTV footage shows Messina leaving the theatre via the stage door shortly after the final curtain. A couple of paces behind him is a blurred figure: a woman in a red dress, dark hair swinging around her shoulders. Her face is invisible, masked by the opera programme that she's holding up as if to fan herself.

As she eats, she watches the eight o'clock news summary on the BBC. There's a warning of a cold front coming in from the east ("Make sure your boilers are serviced!"), an overwhelmingly bleak piece about the economy, and an imported clip of a rally in Moscow, where an impassioned, bearded figure is addressing an attentive crowd in a snow-whitened square. A blurry caption identifies him as Виктор Кедрин.

Why was it necessary to incapacitate Greco in this way before shooting him? It's a question that's nagged Eve for some time, and she's no nearer to finding an answer than she was on the day that she first read the file. Given that the assassination took place in an essentially public location, wouldn't it have made sense to get it over with quickly? Why, with discovery possible at any moment, would the killer want to drag things out?

Eve is still pondering this question when she arrives back at the flat in Finchley a few minutes before eight o'clock. Her husband, Niko, is not there; he's gone ahead to the bridge club where he instructs three evenings a week. He's left a pierogi -- a Polish dumpling dish -- in the oven, which Eve retrieves gratefully. She's not much of a cook and hates having to prepare meals from scratch when she arrives back after a long day at Thames House.

Eve leans forward in her seat, a forkful of pierogi suspended in her hand. Despite the poor image-quality, Viktor Kedrin's magnetism is palpable. She strains to hear his words behind the commentator's voice-over, but the clip cuts to a story of an orphaned kitten adopted by a chihuahua.

When she's finished eating, Eve exchanges her work clothes for jeans, a sweater and a zip-up windproof jacket. The result is unsatisfactory, but she can't be bothered to give it more thought. She looks around the flat, from the waist-high stacks of books in the narrow front hall to the clothes hanging from the drying-rack in the kitchen. If and when I get pregnant, she tells herself, we're going to need somewhere bigger. For a moment, she allows her thoughts to linger on the airy red-brick mansions in Netherhall Gardens, just five minutes' walk away. A first-floor apartment in one of those would be perfect. And about as likely to come into her and Niko's possession as Buckingham Palace. The combined salaries of a Security Services officer and a teacher just didn't stretch to that sort of place. If they wanted somewhere larger, they'd have to move further out. Barnet, perhaps. Or Totteridge. She rubs her eyes. Even the thought of moving is exhausting.

She zips up her windproof. The club is ten minutes away, and as she walks, she thinks of that cold front coming in from the east. It seems to promise not just ice and snow, but menace.

Eve spots Niko Polastri, her husband, straight away. He's playing a practice hand with three beginners, his gaze attentive, his movements economical. Even at a distance Eve can see from their body language how anxious the novices are to impress him. A woman with teased blonde hair leads a card, and Niko regards it for a moment before picking it up and returning it to her with a grave smile. She looks confused for a moment, then her hand flies to her mouth and everyone at the table laughs.

Niko has the gift of imparting knowledge with grace and humour. In the North London school where he teaches maths he's popular with the pupils, who are generally acknowledged to be a tough bunch. At the club, where he is one of four senior instructors, the members compete openly for his approval, with even the flintiest veterans melting at a word of praise for a stylishly executed finesse, or a contract made against the odds.

It's a tournament night at the West Hampstead Bridge Club, and the place is filling fast. The game room is laid out with folding baize-topped tables and stackable plastic chairs. It's warm after the chill of the streets, and there's an animated buzz of conversation round the bar.

Eve met Niko four years ago, when she first joined the club. At the time she was less interested in improving her bridge-playing than in finding a social life disconnected from the intense, inward-looking hive of Thames House. A social life that would hopefully feature an attractive, intelligent man. In her mind's eye she saw a suave figure, his features not quite discernible, leading her up a broad flight of steps to a smart West End restaurant.

The bridge club, whose members had an average age somewhere north of fifty, did not deliver such a man. Had she wished to meet retired accountants and widowed dentists, it would have been just the place, but attractive single men under forty were thin on the ground. Niko wasn't there when she first presented herself; she and a couple of other prospective members were attended to by Mrs. Shapiro, the blue-haired club secretary.

Dispirited by the experience, she was in two minds about going back the next week. But she went, and this time Niko was there. A tall man with patient brown eyes and the moustache of a nineteenth-century cavalry officer, he took charge of Eve from the moment she arrived, squiring her to a table, summoning two more players, and partnering her without comment for half-a-dozen hands. Then, dismissing the others, he faced her over the green baize table.

"The good news is that there's a very nice pub just five minutes away."

Eve meets his gaze. "Is it that obvious?"

She laughed. They were married later that year.

Eve's bridge partner tonight is a young guy, perhaps nineteen, one of a trio of students from Imperial College who joined the club in the autumn. He's got a slightly mad-scientist look about him, but he's a ferociously good player, and at the West Hampstead that's what counts.

"To others, maybe not. You like to play the myszka, the mouse. But I see the fox."

"Exactly. If you're going to play a strategic game, you need to know very early on where all the cards are. To do this, you need to concentrate harder on your opponents' play. You need to remember the bidding, and count every suit."

"A faulty fox?"

"It could be. But you have faults."

"So, Eve. Good news, or not-so-good news?"

"And you like, very much, to win."

"My parents both played, yes."

"Right." She digested this for a moment. "So what's the good news?"

"Not-so-good news first, I think."

"Is that good?"

"OK. Well, you understand the basics of the game. You learnt as a child?"

"So how was your day?" she asks him, linking her arm tightly through his as they make their way back towards the flat. It's just started to snow, and she blinks as the flakes touch her face.

At the end of the evening she thanks her partner. They've finished fourth overall, a good result, and he grins a little awkwardly and shuffles off. At the entrance Niko helps her into her zip-up waterproof jacket as if it was a Chanel coat, a tiny act of chivalry that does not go unnoticed by other female members, who glance at Eve enviously.

After her initial uncertainty, Eve has come to look forward to her evenings here. Some of the members are her parents' age and even, in one or two cases, her grandparents'. But the standard of play is fierce, and after a rigorous day at Thames House she appreciates the idea of intellectual challenge for its own sake.

"The Year 11 boys would have a better understanding of differential calculus if they didn't all stay up until two in the morning playing Final Attrition 2. Or maybe not. How about you?"

Niko knows what she does, and while he never presses her for information Eve often thinks how useful a mind like his would be to her employers. At the same time the thought of him walking the featureless corridors of Thames House fills her with horror. It's her world, but she wouldn't want it to be his.

She hesitates. "I've got a problem for you. I've been trying to figure it out all day."

After leaving Cracow University with a Master's degree in Pure and Applied Mathematics, Niko took off round Europe in a battered van with a friend named Maciek. Living and sleeping in the van, the pair travelled from tournament to tournament -- bridge, chess, poker, anything offering a cash prize -- and after eighteen months on the road, retired with over a million zloty between them. Maciek spent his share in less than a year, mostly on the girls at the Pasha Lounge on Warsaw's Ulitsa Mazowiecka. Niko headed for London.

"OK. Three dead men on the floor of a theatre box, after a performance. Two bodyguards and a Mafia don. All shot. But the don has been tranquillised first. Paralysed by an immobilising agent injected into one eye. What's the story? Why was he not just shot like the bodyguards?"

"Tell me," he says.

"Nasty-looking thing." He blows snow from his moustache. "But clever. And perhaps it wasn't the nephew. Is there a woman involved?"

"How come?"

"The killer's first problem is how to get past the bodyguards with a weapon. These are going to be tough, experienced guys."

"But this, on the other hand…" He holds up the photocopy. "They're not going to give this a second look."

She stares at him. "What makes you say that?"

Niko is silent for a minute. "Who was killed first?"

"I'll show you."

She takes a photocopy of a photograph from her bag. They stop for a moment in a whirl of snowflakes beneath a street light.

"I'm assuming the bodyguards. The shooter, thought to be the don's nephew, used a silencer. Low-calibre weapon at point-blank range."

"And the syringe, or whatever. The immobilising agent. What do we know about that?"

"The don, yes. The bodyguards, back of the neck. No mess. Very professional."

"OK."

He reaches into his coat pocket, and takes out a pen. "Look, if I draw a retaining wire which attaches here, and snaps into place there, what do we have?"

"Body shots?"

Eve stares at the limp photocopy. "Oh for fuck's sake. How can I have missed that?" Her voice is a whisper now. "It's a hairclip. A woman's fucking hairclip."

Villanelle is travelling on a false passport as Manon Lefebvre, the co-author of a French investment newsletter. Her cover story is that she is in London to talk to an online publisher interested in setting up a partnership. She looks professionally anonymous in a mid-length trenchcoat, narrow jeans and ankle boots. She's wearing no make-up, and despite the season, grey-lensed acetate sunglasses; airports attract photographers and, increasingly, law-enforcement professionals armed with facial recognition software.

In the business-class lounge at Charles de Gaulle airport, Villanelle checks her messages. A coded text confirms that Konstantin will meet her at the La Spezia cafe in Gray's Inn Road in London at 2 p. m. as arranged. Returning her phone to her bag she sips her coffee. The lounge is warm, with smoothly moulded seating in restful shades of white and taupe; the walls are flecked with illuminated leaf-shapes. Beyond the plate-glass exterior wall the tarmac, slush and sky are a barely distinguishable grey.

Niko looks at her. "So, is there a woman involved?"

An Air France steward appears in the lounge and directs the business-class passengers to their flight. Villanelle has reserved the front aisle seat in the waiting Airbus, and although she makes a point of not meeting his eye, she can tell that the man in the window seat, currently flicking through an inflight magazine, is determined to engage her in conversation. She ignores him, and taking out a 4G tablet and earphones, is soon immersed in a video clip.

The clip shows, in slow motion, the contrasting terminal performances of two handgun rounds when fired into a block of clear ballistics gelatin, a testing medium designed to simulate human tissue. One round is Russian, one American. Both are jacketed hollow point, designed to deliver massive kinetic shock and remain within a target's body rather than passing through. Knowing that she's likely to be operating in a busy urban environment, this information is of interest to Villanelle. She's going to want a one-shot, lights-out kill. She can't risk the possibility of collateral damage.

It's the stewardess, chic in her dark-blue tailored suit.

"Someone special?"

She frowns, torn between the two hollowpoint rounds. The Russian round expands on entry, its jacket peeling back like the petals of a flower as it blasts through flesh and bone. The U. S. round, by contrast, doesn't deform but tumbles nose over point, tearing a devastating wound cavity as it goes. Both have their very considerable merits.

She noticed him earlier, in the business-class lounge. Late thirties and implausibly good-looking, like a designer-dressed matador.

"But…" He reaches for the inflight magazine, and pages through it until he reaches a fragrance advertisement. "That's not you?"

"Lucky him." He levels a dark-brown gaze at her. "You're Lucy Drake, aren't you?"

"No, for someone else."

"Yes. It's going to be a surprise."

"Actually, I was shopping."

"Could I ask you to switch off your device, Mademoiselle?"

"Of course." Villanelle smiles coolly, blanks the screen and takes out the earphones.

"Excuse me?"

"For yourself?"

"Lucy Drake? The model?"

"Sorry, no."

"Good movie?" asks her companion, seizing his chance.

"She is." He holds out his hand. "Luis Martín."

"It's a compliment. She's lovely."

"So does she have talent?"

"She wants to act, apparently. And she thinks the more editorial and advertising she does, the less chance she has of being taken seriously."

"Really?"

"And this Lucy Drake is on your books?"

"Forgive me," he says. "I was mistaken."

"She has talent as a model, which is very much rarer than you might think. As an actress…" He shrugs. "But then people so often undervalue their real talents, wouldn't you say? They dream of being something they can never be."

"Manon Lefebvre." She looks down at the magazine, now on the armrest between them. "How did you know that model's name, if you don't mind me asking?"

"I'm in the business. My wife and I own an agency, Tempest. We've got divisions in Paris, London, Milan and Moscow."

"No, I think she's with Premier. She's not working so much any more."

Villanelle looks at the page. It's true, the model does look uncannily like her. But Lucy Drake's eyes are a piercing green. The fragrance is called Printemps. Spring. Villanelle takes off her sunglasses. Her own eyes are the frozen grey of the Russian midwinter.

"You should think of modelling," he says. "You have the cheekbones, and the fuck-you stare."

"A little," she says.

"Yes, but I spend very little time in Spain. Our main residences are in London and Paris. Do you know London?"

She considers. Did six weeks' brutal unarmed combat training in the Essex marshes count? A fortnight spent hurtling round hairpin bends on the evasive driving course at Northwood? A week learning to pick locks with a retired burglar on the Isle of Dogs?

"It's a compliment, believe me. What do you do?"

The stewardess is back with champagne. Martín accepts, Villanelle asks for mineral water.

"Thank you very much."

"You're Spanish?" asks Villanelle, deflecting the personal questions that she senses coming.

"Financial stuff. Much less glamorous, I'm afraid. So… was your wife a model?"

The conversation takes its predictable course. Villanelle is guarded on the subject of her alter-ego Manon Lefebvre, and presses Martín for details about Tempest. With two glasses of Veuve Clicquot drunk and a third half-empty, he's only too happy to talk about himself, while simultaneously plying Villanelle with a stream of increasingly flirtatious compliments.

"Elvira? Yes, originally she was. A very successful one. But these days I deal with the clients, and she runs the back office."

Her thoughts drift to that night in Palermo. Say what you like about Leoluca Messina, he didn't have control issues. In fact he was perfectly happy to let her fuck him while she was holding a cocked and loaded Ruger. In its way, the whole episode was quite romantic.

For a moment she wonders if he's a plant from MI5, or France's external intelligence service, the DGSE. But she didn't book the London flight; instead she took a taxi hailed at random outside the Galeries Lafayette on the Boulevard Haussmann, and paid cash for her ticket when she got to the airport. Basic counter-surveillance measures, including a last-second pull-off into a service station on the A1 autoroute, told her that she wasn't followed from Paris. And Martín was in the business-class lounge before her, already checked in. Most importantly, her instincts -- highly tuned when it's a question of her own survival -- tell her that this man is not playing a role. That he really is the over-groomed seducer that he appears to be. The joke about narcissistic types like Martín is that they always think they're in control -- at work, in conversation, during sex.

"Palermo worried me," he tells her. "What you did, driving through the city at midnight on the back of Messina's motorcycle, that was reckless. Things could have gone badly wrong."

Konstantin is sitting in front of the cafe counter, facing the door and Gray's Inn Road. The Evening Standard is open in front of him at the sports page, and he's sipping a cappuccino. When Villanelle walks in, stamping snow from her boots, he looks up, his gaze vague, and nods her to a seat opposite him. The downbeat welcome robs the moment of its potential drama; no one looks up at the young woman in the thrift-shop coat and knitted beanie. She orders a cup of tea, and the pair begin an inaudible conversation. Were anyone to attempt audio surveillance they would find their efforts frustrated by the low-fi snarl of the sound system and the steamy hiss and cough of the Gaggia coffee machine.

For thirty minutes, as customers come and go, they discuss logistics and weaponry in fast, idiomatic Russian. Konstantin tests Villanelle's plan to destruction, throwing up objection after objection, but finally concedes its workability. He orders a second cappuccino, and stirs his cup meditatively.

He stops, annoyed that his concern for her has momentarily become personal. From the first, in that hut by the Chusovaya river, he has sensed the cross-currents of sex and death swirling beneath her icy surface. Known that the implacable hunger that drives her could also destroy her. For a moment, she looks almost vulnerable.

"I improvised. I was in control throughout."

"Go on."

"Listen to me, and listen well. You are never completely safe. And you can never fully trust anyone."

"Not even you?"

"Yes, Villanelle, you can trust me. But part of you should always be mistrustful, questioning and attuned to danger. Part of you shouldn't fully trust me. I want you to survive, OK? Not just because you're so good at what you do, but…"

His eyes rake the busy cafe. "Look, right now, no one knows for sure that you even exist. But what happens this week could change everything. The British are a vengeful people. If you give them half a chance, their security services will come after you with everything they've got, and they will not back off."

She nods, and even in the winter dimness of the cafe he can see that her eyes are shining.

"So it's important, this action?"

"They're the people who decide how history is to be written. We are their soldiers, Oxana. Our job is to shape the future."

"It's vital. Our employers don't take these decisions lightly, but this man must be eliminated."

With a finger, she traces a V in spilt tea on the melamine surface of the table. "I sometimes wonder who they are, these employers of ours."

"Oxana is dead," she murmurs.

Later, high above South Audley Street in Mayfair, she looks westwards. Beyond the floor-to-ceiling window the sky is umber in the twilight, and the trees are grey. Snowflakes drive silently against the plate glass.

"And Villanelle must survive."

The top-floor apartment is registered in the name of a corporate finance group. There's a TV suite and a state-of-the-art sound system, which Villanelle will not use, and a fully provisioned kitchen, which she will leave only slightly depleted. For the next forty-eight hours she will spend much of her time here in the bedroom, sitting as now in a white leather Charles Eames chair, waiting. There are moments when she would welcome the sting of loneliness. Instead, she feels a level blankness, neither happy nor unhappy. She senses a rising of the tide, an echo of the action to come. Konstantin will do his part, but in the end there will just be her, and Kedrin, and the moment.

She touches a finger to her mouth, to the faint ridge of the scar. She was six when her father brought Kalif home. A hunting dog rejected by its previous owner, the animal attached itself devotedly to Oxana's mother, who was already gravely ill. Oxana wanted Kalif to love her, too, and one day she climbed onto the steel-framed bed in which her mother passed her increasingly pain-wracked days and nights, and pressed her face close to the dog, which was curled up on the thin blanket. Baring sharp teeth in a vicious snarl, Kalif struck out at her.

Villanelle could easily have her upper lip remodelled by a plastic surgeon, so that it curves into the perfect bow that nature intended, but she hasn't done so. The scar is the last vestige of her former self, and she can't quite bring herself to erase it.

There was a lot of blood, and Oxana's torn lip, stitched without anaesthetic by a medical student from a neighbouring apartment, was slow to heal. Other children stared at her, and by the time the wound ceased to be noticeable Oxana's mother was dead, her father was in Chechnya and Oxana herself had been consigned to the tender mercies of the Sakharov Orphanage.

From nowhere she feels a morbid crawl of desire. Rolling onto her side on the white leather, she presses her thighs together and clasps her arms across her small breasts. For several minutes she lies like this, her eyes closed. She recognises it, this hunger. Knows that it will tighten its grip unless satisfied.

She showers, dresses, and slicks back her hair. The lift conveys her soundlessly to the ground floor, and the street. She blinks as the first whirling snowflakes find her face. Cars pass with a faint hiss of tyres, but there aren't many people on foot, except a prostitute in a faux leopardskin coat and platform heels waiting on the corner of Tilney Street, patiently eyeing the forecourt of the Dorchester Hotel. Walking northwards, navigating on impulse, Villanelle turns from South Audley Street into Hill Street, then through an archway into a narrower road leading to a square so small it's almost a courtyard. One side is taken up by a brightly illuminated gallery window, beyond which a private view is taking place. There's a single spotlit object in the window: a stuffed weasel on a plinth, strewn with bright, multicoloured cupcake sprinkles.

Villanelle stares at it. The sprinkles look like multiplying bacilli. The installation, or sculpture or whatever it is, conveys nothing to her.

The woman -- late thirties, black cocktail dress, wheat-blonde hair pulled back in a chignon -- is leaning out of the glass door of the gallery, holding it half-closed to keep the cold air at bay.

"Are you coming in?"

Shrugging, Villanelle enters the gallery, losing sight of the woman almost immediately. The place is packed with prosperous-looking invitees. A few are looking at the paintings on the walls but most are facing inwards, conversing in tight groups as catering staff edge between them with canapés and bottles of cold Prosecco. Sweeping a glass from one of the trays, Villanelle positions herself in a corner. The paintings seem to have been reproduced from blown-up press photographs and blurry snatches of film. Anonymous, faintly sinister groupings, several with the faces blacked out. A man in a velvet-collared coat is standing in front of the nearest painting, a study of a woman in the back seat of a car, her shocked features lit by photo-flash, her arm raised against the invading lenses of the paparazzi.

There's a long moment's silence. When the woman speaks again, the register of her voice has subtly changed. "What's your name?" she asks.

"So, Manon. This event will take another forty minutes, and then I'm closing the gallery. After that I think we should go and eat yellowtail sashimi at Nobu in Berkeley Street. What do you say?"

"So what do you think?"

The woman looks at Villanelle, takes in the chic Parisian crop and the Balenciaga biker jacket, and smiles. "Are you speaking from experience?"

It's the woman who invited her in. The man in the velvet-collared coat moves away.

Villanelle shrugs. "She's some burnt-out actress. And she's probably wearing no pants."

"That's the point, we don't know. She could be a film star arriving at a premiere, or a convicted murderer arriving for sentencing."

Studying the man's expression -- the faint frown of concentration, the unwavering gaze -- Villanelle duplicates it. She wants to be invisible, or at least unapproachable, until she's finished her drink.

"If she was a murderer she'd be handcuffed, and she'd arrive at the court in an armoured van."

"Manon."

"Who is she, in the painting?" Villanelle asks.

"Is that good?" Sarah asks.

Her name is Sarah, and she had her thirty-eighth birthday a month ago. She's talking about conceptual art, and Villanelle is nodding vaguely but not really listening. Not to the words, anyway. She likes the rise and fall of Sarah's voice, and she's touched, in an abstract sort of way, by the tiny age-lines around her eyes, and by her seriousness. Sarah reminds her, just a little, of Anna Ivanovna Leonova, a teacher at Industrialny District secondary school, and the only adult, except her father, to whom she's ever formed a real, unsimulated attachment.

For two years the teacher nurtured her charge's exceptional academic gifts, and showed endless patience for her graceless, barely socialised behaviour. Then one day, Anna Ivanovna wasn't there. She'd been attacked and sexually assaulted while waiting for a late bus home from school. In hospital the teacher was able to describe her assailant to the police, and they arrested an eighteen-year-old former pupil named Roman Nikonov, who had boasted of his intention to show the unmarried teacher "what a real man felt like." But the police botched the forensics, and in the end Nikonov was released on a technicality.

Villanelle nods and smiles, examining a pearlescent sliver of raw fish before crushing it, pensively, between her teeth. It's like eating the sea. Around them, soft lights touch surfaces of brushed aluminium, black lacquer and gold. There's a whisper of music; conversation rises and falls. Sarah's lips form words, and Sarah's eyes meet hers, but it's Anna Ivanovna's voice that Villanelle hears.

"OK," says Villanelle.

"A teacher at my school."

"Someone?"

"I'm so sorry."

"Cancer. She was just a couple of years younger than you." Cover stories are part of Villanelle's life now. Clothes she puts on, takes off, and hangs up for next time.

Villanelle shrugs. "It was a long time ago."

"Where did you grow up, Manon?"

"With my father. My mother died when I was seven."

"St. Cloud, outside Paris."

"With your parents?"

She's always regretted that it was too dark to see Roman Nikonov's expression when she castrated him in the woods by the Mulyanka river. But she remembers the moment. The smell of the mud, and of the exhaust from his Riga moped. The pressure of his hand on her head, forcing her to her knees. The throttled screams, carrying far out over the water, as she pulled out the knife and hacked his balls off.

"Oh my God. That's awful!"

"I hope she was nice."

"So what did she…"

"Sorry. Miles away. You remind me of someone."

"She was. And she looked like you." Except that she didn't. She was really nothing like Sarah. Why had she thought that? Why had she said that?

"Don't be." Withdrawing her hand from Sarah's, Villanelle opens the menu. "Look at this! Wild strawberry sake jelly. We have to have some."

"Manon!" She feels Sarah's cool hand take hers. "Where are you?"

Villanelle follows her up a narrow flight of stairs. "So it doesn't mean anything at all?"

"What do you think?"

"I don't think anything. I don't care."

Sarah lives in a tiny flat over the gallery. As they walk back there, hand in hand, they leave dark footprints in the new snow.

"So what do you --"

"OK, I get the paintings, but what's that?" Villanelle asks, pointing to the cryptic installation in the gallery window.

Villanelle half-turns and pins her to the wall, silencing her with her mouth. It's a moment that's been inevitable, but Sarah's still taken by surprise.

Sarah keys a code into the keypad by the door. "Well… the stuffed weasel was a present, given to me as a joke. And the sprinkles were in the kitchen. So I put them together. Quite fun, don't you think?"

Much later, she wakes to see Villanelle sitting upright in bed, her lean upper body silhouetted against the first dawn light. Reaching for her, Sarah runs a hand down her arm, feels the hard curves of her deltoid and bicep. "What exactly was it that you said you did?" she asks wonderingly.

"I didn't say."

Villanelle smiles, and touches Sarah's cheek. Dresses quickly. Outside, in the little square, there's virgin snow, and silence. Back at the South Audley Street apartment, she kicks off her clothes and is asleep within minutes.

"Are you going?"

Villanelle nods.

"Will I see you again?"

When she awakes it's past noon. In the kitchen there's a half-full cafetière of Fortnum & Mason's Breakfast Blend coffee, still warm. Several sizeable carrier bags stand by the front door, where Konstantin has left them.

She checks the goods. A pair of tortoiseshell-framed glasses with pale-grey lenses. A parka with a fur-trimmed hood. A black polo-neck sweater, a plaid skirt, black woollen tights and zip-up boots. She tries it all on, walks around, accustoms herself to the look. The outfit needs wearing in, so she drinks a cup of the cooling coffee, leaves the apartment building, and makes her way across Park Lane to Hyde Park.

Again, that umber sky, against which the avenues of leafless beeches and oaks are a darker grey-brown. It's early afternoon but the light is already ebbing. Villanelle walks fast along the slush-banked paths, hands in pockets, head down. There are other walkers, but she barely glances at them. At intervals statues loom out of the dimness, their outlines blurred with encrusted snow. On a balustraded bridge across the Serpentine she pauses for a moment. Beneath a cracked and starred pane of ice the water is a lightless black. A realm of darkness and forgetting to which, on days like this, she feels herself almost hypnotically drawn.

He raises a hand. "See you around."

"Home?" The broken smile suggests they're sharing a private joke.

"That's right. Goodbye."

Hunching into her parka, she walks away. Just some fucked-up weirdo hitting on her. Except that he wasn't. With that lethal English courtliness of his, he's both more and less threatening than that. And familiar, somehow. Is it possible that she's seen him before, perhaps in the course of the counter-surveillance exercises that she performs, almost subconsciously, wherever she goes? Is he MI5?

He wipes snow off the balustrade with his sleeve, and shrugs. "He's a good companion in a war zone."

"And now?"

"You're a soldier?"

Villanelle turns, amazed to hear her thoughts so precisely echoed. He's about thirty, lean-featured, in a well-cut tweed coat with the collar turned up.

He lifts his gaze to the distant glow of Kensington. "Research, you might say."

"Well, good luck with that…" She rubs her ungloved hands together, and blows into them. "The light's going. And so should I."

"Tempting, isn't it?"

"I wasn't planning on doing any swimming."

"You know what I mean. 'To sleep: perchance to dream…'" His eyes are steady, and as dark as the frozen waterway.

"You admire Shakespeare?"

"Used to be."

Angling sharply southwards, she glances back at the bridge. The man has disappeared, but she still senses his presence. Heading northwards for the nearest exit she performs a cleaning run, designed to shake off any tail that she might have picked up. No one follows, no one changes direction, no one speeds up to match her pace. But if they're serious, whoever they are, they'll have a primary team foot-following, and a secondary team on static surveillance, ready to latch on if she burns the primaries.

Forcing herself to breathe steadily, she makes for the Marble Arch underpass network. With its multiple exits, it's a good place to expose and lose a tail. Descending the steps at Cumberland Gate she surfaces beside the Edgware Road, and hovers in a sports shop entrance, watching the reflection of the underpass exit in the plate-glass window. No one glances at her, no one breaks step. Strolling to the Marble Arch entrance, she speed-walks the hundred-odd metres through the underpass, cuts back on herself by Speaker's Corner, and makes for the tube station. On the westbound Central Line platform she lets the first two trains pass, scanning the platform for stay-behinds. The line's busy, and there are several possibles. A young woman in a grey windproof jacket, carrying a backpack. A bearded guy in a reefer jacket. A middle-aged couple holding hands.

Turning eastwards, Villanelle walks along Bayswater Road towards Marble Arch. Not racing, but fast enough to make any tail pick up his or her speed. She stops briefly at a bus stop as if resting her legs, discreetly checking the area for anyone in the calculatedly drab plumage of the professional pavement artist. There's no one obvious, but then if she had one of MI5's A4 teams locked on to her, there wouldn't be.

And perhaps, she tells herself later in the South Audley Street apartment, no one was following me anyway. What would be the point? If the UK Intelligence Services know who and what I am, then it's all over. There won't be an arrest, just a visit from a Special Forces action team, probably E Squadron, and cremation in a municipal waste incinerator. This, according to Konstantin, is the British way, and nothing that Villanelle has seen of the British gives her the slightest reason to doubt him.

Stepping onto the third train, she travels as far as Queensway, and then just as the doors are closing, squeezes out between them. Crossing the platform, she returns eastbound to Bond Street, surfaces, and hails a taxi in Davies Street. For the next ten minutes she sends the driver on a circuitous route through Mayfair. A grey BMW follows them for a time, but then turns eastwards on Curzon Street with an irritable growl. A minute later a black Ford Ka appears in the wing-mirror, and three turn-offs later is still there. As they coast into Clarges Mews, a choke-point, Villanelle hands the driver a fifty-pound note and issues swift instructions. Thirty seconds later the taxi drifts to a halt, blocking the road, and the engine dies. As Villanelle slips out of a rear door, she hears the angry blare of the Ka's horn, but no one follows her down the narrow, brick-walled passageway, and when she doubles back five minutes later, the mews is deserted.

Eve groans. "What time is it?"

But the E Squadron scenario is not going to happen, and with a smooth effort of will, she erases the apprehensions prompted by the afternoon's encounter. Curled like a panther on the white leather Eames chair, she raises a glass of pink Alexandre II Black Sea champagne to the fading light. The wine is neither distinguished nor expensive, but it's a symbol of everything that in her other, earlier life she could never have dreamed of.

And it suits her mood. She's in lockdown now, her focus already narrowing to the moment-by-moment details of the next day's action. Anticipation rises through her, as sharp and effervescent as the bubbles prickling to the surface of the champagne, and with it the ache of the hunger that never completely goes away. She coils and uncoils on the white leather. Perhaps she'll go out and have some more sex. It will help kill a few hours.

Eve buries her face in the warm valley between his shoulder blades, clinging to the last vestiges of sleep. The strangulated coughing of the espresso machine overlays the measured tones of Radio 4's Today programme. She's decided, during the night, to put an SO1 Protection team on Viktor Kedrin.

"Six forty-five," murmurs Niko. "Like every day at this time."

He rubs his eyes. "Not if you don't want milk in your coffee in the morning, myszka. Besides, where else would you like me to put it? There's no room in the kitchen."

Returning from the bathroom, she smacks her shin, not for the first time, on the low, glass-fronted fridge that he bought a month earlier on eBay.

"Shit, Niko, please. Do we have to have this… thing here?"

"OK. Give me a couple of minutes."

Ensuring that the blind is down -- it has a habit of shooting up without warning -- Eve lifts her nightdress over her head, and reaches for her underwear. "I'd argue that we don't need a medical standard refrigeration unit to cool one little milk jug. And if there's no room in the kitchen, it's because it's full of all your stuff."

"Coffee's done," Niko says.

"Ah, suddenly it's all my stuff?"

"OK, Swedish cookbooks? That solar-powered microwave…"

"They're Danish. And that microwave is going to save us money."

"When? This is London NW3. There isn't any frigging sun for eleven months of the year. Either we get rid of some of your stuff, or we move somewhere bigger. And a lot less nice."

"Because of the bees." He knots a dark-brown tie over a silver-grey shirt.

"We can't move."

She dresses quickly. "Why not?"

"One word, myszka. Honey. This summer, we could harvest fifteen kilos per hive. I've spoken to the deli, and --"

"Niko, please. Don't get me started on those fucking bees. I can't go into the garden, the neighbours are terrified of being stung to death…"

They cross the tiny landing, stepping over a stack of back issues of Astronomy Now and an ancient, dented cardboard box marked Oscilloscope Testing Equipment/ Cathode Ray Tube, and descend the stairs.

"I think the First Directorate is working you too hard, Evochka. You need to chill out." He checks the knot of his tie in the hall mirror, and gathering up a pile of exercise books from a shelf, shunts them into a battered Gladstone bag. "You are going to make it back in time for the tournament at the club tonight, aren't you?"

"Yes, I know it all makes sense in the future. Your five-year economic plan. But it's the here and now we have to deal with. I can't live like this. I can't think straight."

"Should do." The calculation being that with an SO1 team on Kedrin, she won't feel duty-bound to attend his lecture, or political rally, or whatever it is.

In the P3 office at Thames House, Simon Mortimer looks inscrutable as he puts down the receiver. "Unless you can come up with a specific reason for changing your mind on Kedrin, it's no go," he tells Eve. "Too short notice."

Eve shakes her head. "That's ridiculous. SO1 could easily have a team in place at half a day's notice. Is the foot-dragging coming from our end, or theirs?"

"Ours, as far as I can tell. There's hesitation to deploy SO1 on the basis of, um…"

Eve pulls on her coat, and Niko sets the state-of-the-art alarm that Thames House has thoughtfully provided. The front door closes, and hand in hand, their breath vaporous, they make their way through the half-light of morning towards Finchley Road tube station.

"The phrase used was 'female intuition.'"

She closes her eyes.

She stares at him. "Seriously?"

"On the positive side, you have made your concern known. Your ass, if I may refer to it as such, is covered."

"Seriously."

"Of what?"

On her screen, Eve calls up an article from Izvestiya. "OK, this is from a speech he gave last month in Ekaterinburg. I'm translating. 'Our sworn enemy, which we will fight to the death, and to which we will never surrender, is American hegemony in all its forms. Atlanticism, liberalism, the deceitful'-- he actually says snake-like --'ideology of human rights, and the dictatorship of the financial elite.'"

"What exactly made you change your mind?"

"Pretty standard stuff, surely?"

"Let's hope." She rubs her eyes. "I suppose I ought to go. Don't much feel like it, but…" She exits the Izvestiya page. "Simon, can I ask you something?"

"I suppose you're right. But really, 'female intuition'? What I said in my memo was that I was concerned that I'd underestimated the potential threat to Kedrin."

"Agreed. But there's a huge tranche of the Russian and former Sov-bloc population who see him as a kind of messiah. And messiahs don't have a long shelf life. They're too dangerous."

"Well, let's hope he says his piece at the Conway Hall and pushes off fast."

"Do you think I should do something about, you know, the way I dress? That female intuition comment makes me worried I'm sending the wrong message?"

"Of course."

"Ah."

He frowns. "Well, I know you're not even slightly like that. And as we're so often reminded, discretion is the keynote of the Thames House style. But I don't think there'd be any harm in your, perhaps, venturing a teensy bit further afield than the Marks and Spencer's Classic and Indigo ranges." He looks at her a little nervously. "What does your husband think?"

"Oh, Niko lives in a fashion universe all of his own. He teaches maths."

The Vernon Hotel is a six-storey edifice faced with grey stone on the north side of High Holborn. Its clientele is, for the most part, as anonymous as its frontage, so reception manager Gerald Watts is happy to give his attention to the strikingly attractive young woman standing before him. She's wearing a fur-trimmed parka, and the eyes that meet his from behind the grey-tinted glasses are bright and direct. Her accent, with its hint of France and suggestion of Eastern Europe (after five years at the Vernon's front desk Gerald considers himself something of an expert in these matters), is charmingly fractured.

"I just don't want to see this department's authority undermined, Simon. We make serious decisions, and we need to be taken seriously."

"Well, I don't want to perpetuate any stereotypes here, but perhaps you and I could go shopping?"

He nods. "Are you busy tomorrow afternoon?"

"Not specially. Why?"

By the time that Eve arrives at Red Lion Square, it's 7.45. Inside the Conway Hall the crowd is about two hundred strong. The majority of those who have come to hear Viktor Kedrin speak are already seated in the Main Hall; a few stand chatting against the wood-panelled walls, while others have found their way up to the gallery. Most are men, but there are a few couples here and there, and several younger women in T-shirts printed with Kedrin's portrait. And there are other more enigmatic figures, male and female, whose predominantly black clothing is imprinted with slogans which might be musical, mystical, political or all three.

Her name, he discovers when he takes her credit card details, is Julia Fanin. She's not wearing a wedding ring; absurdly, this pleases him. Proffering her key-card to Room 416 he allows their fingers to touch. Is it his imagination, or does he detect a flicker of complicity? Indicating with a raised hand that one of his assistants take her valise and show her to her room, he watches the easy sway of her hips as she walks towards the elevator.

She doesn't tell him where she is, just that she can't come, and as always he's understanding. He never questions her about her work, her absences or her late nights. But she can tell that he's disappointed; it's not the first time he's had to apologise for her at the club. I must make it up to him, she tells herself. His patience isn't infinite, nor should it have to be. Perhaps we could go to Paris for a weekend. Take the Eurostar, stay in a little hotel somewhere and walk around the city hand in hand. It must be so romantic in the snow.

Looking around her, Eve feels a little out of place, but not threatened. The hall is filling fast, and the various tribes seem content to coexist. If the individuals present have anything in common, it is perhaps that they are outsiders. Kedrin's audience is a coalition of the disenfranchised. Climbing the stairs to the gallery, she finds a seat at the front on the right-hand side, overlooking the stage and the lectern, and with a rush of guilt, realises that she hasn't called Niko to tell him that she can't make it to the bridge tournament. She searches her bag for her phone.

"Friends, I greet you. And I apologise if my English is not so good. But it gives me pleasure to be here tonight, and to introduce my friend and colleague from St. Petersburg State University. Ladies and gentlemen… Viktor Kedrin."

In the hall, the lights flicker and dim. On the stage a ponytailed man walks to the lectern and adjusts the microphone.

Kedrin is an imposing figure, broad and bearded, in a battered corduroy jacket and flannel trousers. There's applause as he walks out, and a few cheers. Taking her phone from her bag, Eve grabs a shot of him at the lectern.

"It's cold outside," Kedrin begins. "But I promise you, it's colder in Russia." He smiles, his eyes dead-leaf brown. "So I want to talk to you about the spring. The Russian spring."

Rapt silence.

"In the nineteenth century there was a painter named Alexei Savrasov. A great admirer, as it happens, of your John Constable. Naturally, like all the best Russian artists, Savrasov succumbed to alcohol and despair and died penniless. But first, he created a very fine series of landscape paintings, the best known of which is called The Rooks Have Come Back. It's a very simple painting. A frozen pond. A distant monastery. Snow on the ground. But in the birch trees, the rooks are building their nests. Winter is dying, spring is coming.

Eve scans the ranks of the audience. Sees the rapt gazes, the mute nods of agreement, the desperate yearning to believe in the golden age that Kedrin promises. In the centre of the front row is a young woman in a black sweater and plaid skirt. She is a few years younger than Eve, and beautiful, even at a distance. On impulse, Eve raises her phone, and surreptitiously zooming in on the woman's face, photographs her. She catches her in profile, lips parted, gazing fervently up at Kedrin.

"And this, my friends, is my message to you. Spring is coming. In the Russian heartland, there is a yearning for change. And I feel the same thing in Europe. A longing to throw off the dictatorship of capitalism, of degenerate liberalism, of America. A longing to reclaim an older world of Tradition and the Spirit. So I say to you, join us. Leave the U. S. to their pornography, their blood-sucking corporations and their empty consumerism. Leave them to their Reign of Quantity. Together, Europe and Russia can build a new Imperium, true to our ancient cultures, true to the old beliefs."

The speech gathers pace. Kedrin recalls another who dreamt of a new imperium -- a thousand-year Reich, no less -- but dismisses the Nazis for their crude racism and lack of higher consciousness. He makes an exception of the Waffen-SS, from whose rigorous idealism, he says, much can be learned. This is too much for one audience member, a middle-aged man who stands up and starts shouting incoherently at the stage.

Kedrin smiles beatifically. "There's always one, no?"

Within seconds, two figures in quasi-military clothing appear from the shadows at the back of the hall, grab the man, and half-lead him, half-drag him towards the exit. A half-minute later, to desultory cheers, they return without him.

In all, he speaks for about an hour, setting out his mystical, authoritarian vision for the northern hemisphere. Eve is appalled but fascinated. Kedrin is charismatic, and satanically persuasive. That he will make true believers out of those assembled here tonight, she is in no doubt. He is not yet well known in Europe, but in Russia he commands a growing following, and has a small army of dedicated street fighters ready to do his will.

"And so my friends, I finish as I started, with that simple message. Spring is coming. Our day is dawning. The rooks have come back. Thank you."

Kedrin's certainly registered her, and gives her a glance as if to say: wait, just let me finish with these people and you'll have my full attention. Soon, watched with barely suppressed amusement by the shaven-headed foot soldiers, the two of them are deep in conversation. Her body language -- the head fetchingly tilted, the neat little breasts out-thrust -- makes her availability unambiguously clear. But eventually she settles for shaking his hand, pulls on her parka, and vanishes into the night.

Slowly, as Eve watches from the gallery, the hall empties. The spectators have a dazed look, as if waking from a dream. After a couple of minutes, accompanied by the ponytailed master of ceremonies and flanked by the two foot soldiers who ejected the protester, Kedrin appears in the auditorium. He is quickly surrounded by admirers, who take it in turn to address a few words to him and shake his hand. The woman from the front row waits on the outskirts of the group, a faint smile touching her sharp, cat-like features. If I dressed like that I'd look like a librarian, Eve muses. So how come this little fascist princess gets to look like Audrey Hepburn?

As one, the audience rises to its feet. As they cheer, stamp their feet, and applaud, Kedrin stands at the lectern, unmoving. Then, with a small bow, he leaves the stage.

Eve is one of the last to depart the hall. She waits outside at a nearby bus stop, and when Kedrin and his party leave the building, she follows them at a discreet distance. After a couple of minutes the four men turn into an Argentinian steak restaurant in Red Lion Street, where they are clearly expected.

Deciding to call it a night, Eve makes for Holborn tube station. It's gone 9.30, and she's too late for the bridge tournament. But she'll get to the club in time to grab herself a large vodka and cranberry juice and watch Niko play a few hands. She needs to wind down. One way and another, it's been a weird day.

At a little after 9.45, when she's satisfied that the Russians are settled in, Villanelle moves away from the doorway from where she's been watching the steak house, and takes a back route to the hotel. As she moves through the lobby towards the lifts, her face shadowed by her fur-trimmed hood, she directs a smile and a brief flutter of her leather-gloved fingers at the reception desk, where Gerald Watts is still on duty.

Back in her room she switches on an iPod-sized UHF receiver, and inserts one of the in-ear headphones. Nothing, as she expected, just a faint, ambient hiss. Pocketing the receiver, leaving one ear-bud trailing, she takes a waterproof case from the valise. Inside, each component lying in its bed of customised foam, is the weapon she ordered from Konstantin: a polymer-bodied CZ 75 9mm handgun and an Isis-2 suppressor. Villanelle prefers a lightweight action on a combat weapon, and the CZ's trigger-pull weight has been adjusted to two kilos for double-action firing, and one kilo for single action.

Letting herself into Room 416, Villanelle opens the valise, takes out a packet of surgical gloves, and exchanges a pair for the leather ones she's wearing. Then, from a sealed polythene bag, she takes a micro-transmitter the size of a fingernail, and a pinch of Blu-Tack. Placing this in the pocket of her parka, she leaves the room and takes the stairs up to the fifth floor, where she seems to straighten a picture on the wall outside Room 521. This done, she continues upwards to the sixth floor, where the stairs terminate in an exit to the roof. It's unlocked, and stepping outside she conducts a quick reconnaissance of the area, noting the placement of chimney stacks and fire-escape ladders. Then, without hurry, she returns to the fourth floor.

Hotel-room assassination, she knows, is a complex science. Taking down the target is easy; it's doing so swiftly, silently and without collateral damage that's difficult. There must be no recognisable gunshot report, no scream of alarm or pain, no bullets smacking through plasterboard partition walls, or worse, through the guests on the other side of them.

So after attaching the suppressor, Villanelle loads the Czech handgun with Russian-made Chernaya Roza -- Black Rose -- hollowpoint rounds. These are constructed with an oxidised copper jacket whose six sections, on impact, peel back like petals. This slows penetration, initiates a massive and incapacitating shockwave, and causes enhanced disruption of tissue along the wound path. For a 9mm round, the Black Rose's stopping power is unequalled.

Villanelle waits, her breathing steady. Visualises and re-visualises the coming course of events. Replays every conceivable scenario. Through the headphones, she hears hotel guests bid each other goodnight, snatches of laughter, doors closing. It's more than an hour and a half before she hears what she's been waiting for: voices speaking Russian.

"Come in for five minutes. I've got a bottle of Staraya Moskva. We need to run over arrangements for tomorrow."

Again, Villanelle waits. It's past 1 a. m. when the security team finally, and noisily, leaves the room. But how drunk is Kedrin? Will he remember the wide-eyed young woman he met at the Conway Hall? She picks up the hotel phone and dials Room 521. A slurred voice answers. "Da?"

Villanelle considers. The drunker they all are, the better. But she can't leave it too late. She hears murmurs of assent, and the sound of the door closing.

Silence. "Where are you?"

She answers in English. "Mr. Kedrin? Viktor? It's Julia. We spoke at the lecture. You said to call you later. Well… it's later."

"Here. At the hotel."

"Yes. I'll come up."

She puts on the parka. The valise is now empty except for a clear plastic evidence bag. Opening this, Villanelle shakes its contents into the valise, which she then stows in the wardrobe. The evidence bag goes into the inside pocket of her parka. Then, after a last look around the room, she leaves, holding the CZ 75 by the suppressor so that the body of the handgun is up her sleeve.

"OK. I gave you my room number, yes?"

"A toast," he says blearily, his eyes dropping to her breasts. "We must have a toast. To love. To beauty!"

"Can I come in?" she asks, tilting her head and looking up at him.

Outside Room 521, she taps lightly on the door. There's a pause, and it opens a few inches. Kedrin is flushed, his hair awry, his shirt open halfway to the waist. His eyes narrow as he examines her.

She slips off her parka and drops it into an armchair, the CZ 75 concealed in the sleeve. A side table holds an empty bottle of Staraya Moskva vodka and four used glasses. Villanelle checks the fridge. In the freezer there's a plastic half-bottle of duty-free Stolichnaya. Uncapping the bottle, she pours a liberal amount into two of the glasses, and meeting his gaze, hands him one.

He bows, semi-ironically. Ushers her in with a vague, sweeping gesture. The room is similar to Villanelle's own, but larger. An ugly gilt chandelier hangs from the ceiling. "Take off your coat," he says, sitting down heavily on the bed. "And get us a drink."

Villanelle smiles. "I drink to our ruined home…" she begins, speaking Russian. "And to life's evils, too…"

The eyes narrow in the skull-like head. Some instinct tells him that something is wrong. That he's fucked up. He tries to look past her, and realises far too late that the Glock 19 that he collected from the driver this morning is in his shoulder holster, not in his hand. Villanelle puts two rounds through the base of his nose, and as his knees go, catches the front of his flight jacket and swings him back through the door of the room. He falls backwards, hitting the monogrammed hotel carpet like a ton of condemned beef.

"… I drink to you," murmurs Villanelle, completing the couplet as she pulls the bedclothes over him. Quickly, she pulls on the parka and makes for the door. As she's leaving the room, she finds herself face to face with one of Kedrin's pet thugs. He's broad-shouldered, scowling, and smells of cheap cologne.

He stares at her for a moment, his expression at once surprised and melancholy, and continues the Akhmatova poem. "I drink to the loneliness we share." He throws back the vodka. "And I drink…"

There's a sound like a snapping stick, and Kedrin is dead. Blood jets briefly from the entry wound beside his left nostril.

"Ssshh," hisses Villanelle. "Viktor's sleeping."

Villanelle races up the stairs to the sixth floor, continues upwards, and bursts out into the night. The roof is virgin white, and a blizzard of snow swirls around her as she bolts the stairwell door. Visibility is no more than a few feet. She has perhaps fifteen seconds start.

She briefly considers dragging the body out of view, but it will take more time than it will save. Then the phone in the room starts ringing, and she knows she has to get out. Making for the stairs she passes Skull-Head's colleague and Ponytail, hears them running to Kedrin's room. One look inside the door and they're after her, pounding along the corridor.

The door splinters and the lock flies outwards. The two men come out fast, breaking left and right respectively, leaving the door swinging in the icy wind. The roof is deserted. Footsteps lead from the stairwell to a balustrade, beyond which is whirling darkness.

Suspecting a trap, the two men duck behind a chimney stack. Then, very slowly, the younger man leopard-crawls across the snowy roof to the balustrade, peers over, and beckons cautiously to Ponytail. There, just visible, is Villanelle, with her back to them, the parka whipping around her body in the wind. She appears to be watching the chimney stack.

Like lovers, the two men fold into each other. And stepping up from the fire-escape ladder, unknotting the sleeves of her parka from the flue-pipe, Villanelle watches them die. As always, it's fascinating. There can't be much brain-function left after a Black Rose round has bloomed inside your cerebellum, clawing its way through your memory, instincts and emotions, but somehow, some spark lingers on. And then, inevitably, dims.

Both men discharge their weapons, and seven suppressed headshots tear through the parka hood. When the slight figure doesn't fall they freeze; there's an instant of terrible comprehension, and then their heads twitch in near unison as Villanelle squeezes off two shots from the fire escape behind them.

Standing there on the rooftop, in her cage of snow, Villanelle feels the longed-for power-surge. The feeling of invincibility that sex promises, but only a successful killing truly confers. The knowledge that she stands alone at the whirling heart of events. And looking around her, with the dead men at her feet, she sees the city resolved into its essential colours. Black, white and red. Darkness, snow and blood. Perhaps it takes a Russian to understand the world in those terms.

That Saturday is, without exception, the worst day of Eve Polastri's life. Four men shot dead on her watch, an A-grade assassin on the loose in London, her MI5 superiors incandescent, the Kremlin no less so, a COBRA group convened, and -- it goes without saying -- her Thames House career fucked.

When the office ring to tell her that Viktor Kedrin has been found shot dead in his hotel room, she's still in bed. At first she thinks that she's going to faint, and then, staggering to the bathroom, and finding the corridor blocked by Niko's bicycle, she vomits all over her bare feet. By the time Niko reaches her, she's crouched on the floor in her nightdress, ash-grey and shaking. Simon rings while Niko is sitting with her in the kitchen. They agree to meet at the Vernon Hotel. Somehow, she manages to get dressed and drive there.

There's quite a crowd in Red Lion Street, held at bay by a barrier of crime-scene tape and two police constables. The senior investigating officer at the scene is DCI Gary Hurst. He knows Eve, and hurries her into the hotel, away from the probing camera lenses. In the reception area, he directs her to a banquette, pours her a cup of sugary tea from a Thermos flask, and watches as she drinks it.

"Yeah. Thanks, Gary." She closes her eyes. "God, what a shit-storm."

"So what have we got?"

"Yeah."

"Four dead. Shot at close range, all headshots, definitely a pro job. Victim one, Viktor Kedrin, Russian, university professor, found dead in his room. With him, victim two, late twenties, looks like hired muscle. On the roof, victims three and four. We think three is Vitaly Chuvarov, supposedly a political associate of Kedrin's, but almost certainly with organised crime connections. Four is more muscle. All armed with Glock 19s except for Kedrin. The pair on the roof discharged seven shots between them."

"Better?"

"Simon?"

"Maybe. Maybe they just feel happier if they're carrying. Do you want to get suited up and go upstairs? The other Thames House guy's waiting for you up there."

"Suggests they were expecting trouble."

"Staging area that way." He points. "I'll be up in a minute."

"Well, it's a colourful one. I'll say that."

The DCI shrugs. "Easily done."

"Sure. Where do I change?"

"Must have picked up the weapons here."

She copes, though, and with Simon standing businesslike and imperturbable beside her, makes herself remember the details. The raised, greyish rims of the entry wounds, the thin trails of blackened blood, the faraway expressions. Kedrin, his sightless eyes directed at the ceiling, has a slight frown on his face, as if he's trying to remember something.

"You did your best," says Simon.

In the staging area Eve is handed a white Tyvek coverall, a mask, gloves and bootees. When she is finally suited up, dread floods through her. She's seen plenty of photographs of gunshot victims, but never any actual corpses.

She shakes her head. "I should have insisted. I should have made the right decision in the first place."

He shrugs. "You made your concerns known. And you were overruled."

She's about to answer when DCI Hurst calls her name and beckons to her from the top of the stairs.

"Thought you'd like to know. Julia Fanin, twenty-six. Left the hotel in the early hours of the morning. Bed not slept in, but an empty overnight bag left in her fourth-floor room. Forensics in there now."

"What do the front desk say?" Eve asks.

"They say she's a looker. We're going through the CCTV footage."

A dark certainty fills Eve. She feels beneath her Tyvek suit for her phone. Calls up the photograph of the woman at the meeting. "Could that be her?"

Eve is telling him about the meeting when his phone rings, and he holds up a hand. Listens in frowning silence.

"OK," he says. "Turns out the credit card she showed the hotel when she checked in yesterday was stolen at Gatwick airport a week ago, from the real Julia Fanin. But we've got fingerprints and hopefully DNA from the overnight bag, and we're soon going to have some CCTV stills. Can you stick around?"

"For as long as it takes." She glances at Simon. "I'm afraid that shopping trip's going to have to wait."

The DCI stares at it. "Where did you get this?"

That afternoon Eve attends a meeting at Thames House, in the course of which she is questioned in detail as to her decision concerning Kedrin's protection and her subsequent change of mind, debriefed about the police inquiry, and finally, ordered to take ten days' home leave. That she will return to the office to discover she has been demoted or reassigned is a foregone conclusion.

The accommodation that they reached, early on in their marriage, was that while her working hours belonged to Thames House and the Service, at the end of the day she came home to him. What they shared -- the complicity and intimacy of their evenings and nights -- was infinitely more important than the things that they couldn't.

At home, she can't settle. There are a hundred things to do about the flat -- sorting, storing, cleaning, tidying -- but Eve can't bring herself to embark on any of them. Instead she goes for long, directionless walks through the snow on Hampstead Heath, constantly checking her phone. She's given Niko the bare bones of the situation and he doesn't press her for more, but she can tell that he's hurt and frustrated by his inability to help. She's always known that the secrecy aspect of intelligence work imposes its own unique strains on a marriage; what's shocking is just how corrosive it proves to be. How her silence eats away at the very foundations of the trust between herself and Niko.

The DNA analysis on the hair samples found in the valise, a rush job by the forensic lab, has come up with a match on the UK database. An arrest has been made at Heathrow. Can Eve come to Paddington Green Police Station to assist with identification?

The Sunday papers make what they can of the case. The Observer hints at possible Mossad involvement, and the Sunday Times speculates that Kedrin might have been eliminated on the orders of the Kremlin because his increasingly fascist outpourings were beginning to embarrass the president. The police, however, release no more than the barest details. Certainly nothing about a female suspect. And then, on Wednesday morning, just as her toast is beginning to brown -- Niko usually prepares breakfast, but he's already at work -- Eve gets a call from DCI Hurst.

But the Kedrin murder spreads like a toxin into every aspect of her life. At night, instead of slipping into bed beside Niko and healing the rifts of the day by making love, she stays up until the early hours of the morning scanning the Internet, and hunting for new reports on the killings.

Eve can, and as she replaces the receiver, the smoke alarm goes off. Throwing the burning toast into the sink with a pair of salad tongs, she opens the kitchen window, and stabs vainly at the alarm with a broom-handle. I'm really not cut out for this domestic stuff, she thinks bleakly. Perhaps it's just as well I'm not pregnant. Not that that's exactly a likelihood, with the way things are going.

Paddington Green Police Station is a brutal, utilitarian building that smells of anxiety and stale air. Beneath ground level is a high-security custody suite where prisoners suspected of terrorist offences are held. The interview room is grey-painted and strip-lit; a one-way glass window takes up most of one wall. Eve and Hurst sit beneath it, with the prisoner sitting opposite them. It's the woman who was at Kedrin's lecture.

Eve is expecting to feel a fierce triumph at the sight of her. Instead, as at the Conway Hall, she's struck by her beauty. The woman, probably in her mid-twenties, has an oval, high-cheekboned face, framed by a dark, glossy bob. She's simply dressed in black jeans and a grey T-shirt that shows off her slender arms and neat, small-breasted frame. She looks tired, and more than a little confused, but no less graceful for all that, and Eve is suddenly conscious of her own shapeless hoodie and untended hair. What would I give to look like that? she wonders. My brain?

"Please state your name," Hurst says to her.

The woman leans forward towards the voice-recorder. "My name is Lucy Drake."

She darts a look at Eve. Her eyes, even beneath the strip-lights, are a vivid emerald. "I'm an actress. An actress and model."

"And what were you doing at the Vernon Hotel in Red Lion Street, last Friday night?"

"And your profession?"

Hurst introduces himself and "my colleague from the Home Office," and switching on the voice-recorder, officially cautions the suspect, who has elected to dispense with the services of a lawyer. And looking at her, Eve suddenly knows that something is wrong. That this woman is as incapable of murder as she is. That the police case is about to fall apart.

Lucy Drake gazes thoughtfully at her hands, which are folded on the table in front of her. "Can I start at the beginning?"

Even as her heart sinks at how completely she and the police have been blindsided, Eve can't help but admire the elegance of the deception.

It all started, Lucy explains, with a call received by her agent. The client represented himself as belonging to a production company that was making a television series about different aspects of human behaviour. In this connection, they needed an attractive, confident young actress to undertake a series of social experiments, in which she would play a number of roles. The filming would take place over five days in London and Los Angeles, and the successful applicant would be paid four thousand pounds a day.

"When it came to my turn Peter asked me to role-play a couple of scenes with him. One where I was booking into a hotel and I had to make the desk guy fall for me, and one where I had to approach a speaker after a lecture and seduce him, basically. The idea in both scenarios was to be super-flirty and charming but not come across like a hooker. Anyway, I gave it my best shot, and when I'd finished, he asked me to wait downstairs in this Cuban teahouse place and order anything I wanted. So I did, and forty minutes later he came down and said congratulations, I've seen everyone and the job's yours."

"It was all a bit vague," Lucy says. "But given the fee, and the exposure the programme would bring, I wasn't too worried. So that afternoon I took the tube from Queen's Park, where I live, to the St. Martin's Lane Hotel, where they were holding the interviews. The director was there -- Peter something, I think he was Eastern European -- and a cameraman who was videoing everyone. There were several other girls there, and we were called in one by one.

Leaving the bag in the room, she was to walk to the Conway Hall, around the corner in Red Lion Square, and buy a ticket to the 8 p. m. lecture given by Viktor Kedrin. After the lecture she was to gain personal access to Kedrin, charm and flatter him, and arrange to meet him at his hotel later that night. With that done, she was to meet Peter on the corner of the square, give him her hotel room key-card, and take a taxi home to Queen's Park.

The following morning, Lucy was told, Peter would pick her up early, drive her to Heathrow, and put her on a plane to Los Angeles. There she would be met, put up at a hotel, and given instructions for the second stage of filming.

Over the next two days "Peter" went through everything that Lucy was required to do. She was measured for the clothes that she would wear, and told that this "costume" had to be precisely adhered to, with no changes or substitutions. On Friday afternoon she was to book into the Vernon Hotel under the name of Julia Fanin and take an overnight bag up to her room. Peter would provide the credit card that she would use and also the bag, which she was not under any circumstances to open.

"Yes. He came round at 6 a. m. with a first-class return to LA, and I was in the air by nine. I was met at the airport by a driver who took me to the Chateau Marmont, where I got a message that the filming had been cancelled, but I was welcome to stay on at the hotel. So I used the time to go and see some acting agents, and at midday yesterday caught the return flight to Heathrow. Where I was, um… arrested. For murder. Which was kind of a surprise."

"Do you think we're ever going to get a useful description of this Peter character?" Eve asks.

"Really?" asks Hurst.

"And that's how it worked out?" asks Hurst.

An hour later, Eve and Hurst are standing on the steps at the rear of the police station, watching as an unmarked BMW turns out of the car park, headed for Queen's Park. Hurst is smoking. As the BMW passes, Eve catches a final glimpse of the flawless profile that she photographed in the Conway Hall.

"Yes, really." Lucy wrinkles her nose and looks around the interview room. "You know, there's a really weird smell of burnt toast in here."

"Unlikely. We'll bring Lucy back to help us make up a Photofit when she's had a few hours' sleep, but I'm not hopeful. It was all far too well planned."

"No. I don't. We'll check her story out in detail, obviously, but my guess is that she isn't guilty of anything except naivety."

"And you really don't think she was in on any of it?"

Eve nods. "She so much wanted it to be true. The successful audition, the big break into TV…"

"Yeah." Hurst treads out his cigarette on the wet concrete step. "He played her just right. And us, too."

Eve frowns. "So how do you think two of Lucy's hairs came to be in that overnight bag, if she never opened it?"

"My guess would be that Peter, or one of his people, took the hairs during the fake audition, perhaps out of her hairbrush. And then our shooter drops them in the bag after she's taken Lucy's place in the hotel. And here's a question for you. Why Los Angeles? Why go to the trouble of flying that girl halfway round the world when she's already played her part?"

"That's easy," says Eve. "To make sure she's out of the picture by the time the news of the murder breaks. They can't risk her reading about it online, or hearing about it on the radio, and going straight to the police with what she knows. So they make sure that she's taking off for LA -- an eleven-hour flight -- at the precise time that the murder's discovered on Saturday morning. Which not only renders Lucy incommunicado, but also sets a perfect false trail, giving the real killer and her team plenty of time to cover their tracks and vanish."

"She's going to stay for the duration, exactly. She may, just possibly, see or read something about Kedrin, but that's all happening on the other side of the world. Meanwhile, she's got Hollywood agents to see. That's what's going to be uppermost in her mind."

Hurst nods. "And once she's at the swanky Sunset Boulevard hotel…"

"Yeah, well, cheeky or not, that woman shot four foreign nationals dead on our turf. Can we go back and see that CCTV footage again?"

"And then, when they're ready, and the DNA results are in, they serve her up to us on a plate." He shakes his head. "You have to admire their cheek."

"Absolutely."

It's been edited into a single, silent loop. Lucy Drake walking into the hotel foyer in her parka, carrying the valise, and checking in, the suggestiveness of her body language apparent. Lucy exiting the lift on the fourth floor and walking to Room 416. Lucy leaving the hotel without the valise, raising the hood of her parka as she goes.

"OK stop," Eve says. "That's the last of her, agreed? From now on the woman in the parka is our killer."

"Look at her planting that bug outside Kedrin's room," says Hurst. "She knows she's on camera, but she doesn't care, she knows we can't make her. You have to admit, Eve, she's good."

"Agreed," says Hurst.

"You weren't able to pull any prints off the bug, or anywhere else?"

He runs the footage in x16 slow-motion. Infinitely slowly, as if moving through treacle, the hooded figure enters the hotel, lifts a blurry hand in the direction of the front desk, and vanishes out of shot. Her face is invisible, as it is throughout the footage in the hotel corridors.

"Look closely. Surgical gloves."

"Motherfucker," Eve breathes.

Hurst raises an eyebrow.

"She's a murdering bitch, Gary, and she's cost me my job. I want her, dead or alive."

At their Avenue Kléber apartment, Gilles Mercier and his wife Anne-Laure are entertaining. Among those at dinner are a junior minister from the Department of External Trade, the director of one of France's major hedge funds, and the executive vice president of Paris's most important fine art auction house. Given the company, Gilles has gone to considerable trouble to ensure that everything is just so. The food has been catered by Fouquet's on the Champs-élysées, the wine (2005 Puligny-Montrachet, 1998 Haut-Brion) is from Gilles's own carefully curated cellar, and precisely dimmed spotlights pick out the cabinet of ormolu clocks and the two Boudin oils of the beach at Trouville, which the executive vice president has recognised as fakes, and indeed has whispered as much to his younger male companion.

"Good luck with that," says Hurst.

"So how was London?" he enquires. "I was there in November. Were you very busy?"

The conversation among the men has covered predictable ground. Immigration, the fiscal naivety of the socialists, the Russian billionaires forcing up the price of holiday homes in Val-d'Isère and the Ile de Ré, and the upcoming season at the Opéra. Their wives and the executive vice president's friend, meanwhile, have covered the new Phoebe Philo collection, the fabulousness of Primark pyjamas, the latest Ryan Gosling film, and a charity ball that the hedge-fund director's wife is organising.

"Yes, work's always murder. But it was lovely to be there. Hyde Park in the snow. The Christmas lights, the pretty shop windows…"

"And in the evenings?" He allows the question to hang suggestively in the air.

Invited by Anne-Laure to balance the numbers, Villanelle is bored senseless. The junior minister, whose knee has nudged hers more than once under the table, is questioning her about her activities as a day-trader, and she is answering in evasive generalities.

"Alone? In your Primark pyjamas?" This time it's his hand that finds her knee.

"In the evenings, I read and went to bed early."

"Precisely. I'm afraid I'm a rather dull girl. Married to my work. But can I ask you, who does your wife's hair? That layered style looks lovely on her."

The junior minister's smile grows fainter, and his hand moves away. The minutes tick by, glasses and plates are filled and refilled, élysée Palace rumours and fifty-year-old Armagnac circulate. Finally the evening winds down and the guests are brought their coats.

"Are you sure?" murmurs Villanelle, eyeing Gilles, who is corking bottles and issuing instructions to the caterers.

"Come on," says Anne-Laure, grabbing Villanelle by the arm. "Let's go, too."

Five minutes later, the two of them are rounding the Arc de Triomphe at speed in Villanelle's silver Audi Roadster. It's a cold, clear night with tiny flecks of snow silvering the air. The Roadster's roof is lowered and Hélo?se Letissier is blasting from the sound system.

"I'm sure," hisses Anne-Laure. "If I don't get out of this flat right now I'm going to scream. And look at you, all dressed up. If ever I saw a girl who needed an adventure…"

"Where are we going?" Villanelle shouts, the icy wind whipping at her hair as they swing onto the Avenue des Champs-élysées.

"Doesn't matter," Anne-Laure mouths back. "Just drive."

On the penultimate day of her enforced leave, an envelope bearing Eve's name falls through the letterbox of the flat. The writing paper is headed with the imprint of the Travellers Club, in Pall Mall. The unsigned message, handwritten in slanting italics, is short and to the point:

Villanelle puts her foot down, and whooping and laughing, the two women race into the glittering darkness of the Paris night.

Please come to the office of BQ Optics Ltd. Second floor, above Goodge Street Underground station tomorrow (Sunday) at 10.30 a. m. Bring this letter with you. Confidential.

Eve reads the note several times. The Travellers Club writing paper suggests that the correspondent has Security Services or Foreign Office connections, the fact that it is handwritten and hand-delivered suggests an entirely sensible distrust of email. It could of course be a hoax, but who would bother?

The entrance to the BQ Optics office is on Tottenham Court Road. Noting it as she exits Goodge Street tube station, she crosses the road and watches the place for five minutes from outside Heal's, the furniture store. The tube station and the first-floor offices are faced with brown glazed tile, and surmounted by a dingy residential block. The second-floor offices appear deserted.

But when she presses the bell at the side of the entrance, she is buzzed in immediately. A staircase leads to the first floor, the headquarters of a recruitment agency, and thence by narrower stairs upwards. The door to the BQ Optics office is ajar. Feeling a little foolish, Eve pushes it open and stands back. Nothing happens for a moment, then a tall figure in an overcoat steps into the dusty light.

At 9.30 the next day she leaves Niko sitting at the kitchen table amid a sea of pamphlets. He's assessing the costs and benefits of converting the attic into a miniature hydroponic farm, sustained by low-energy LED lighting, and producing pak choi and broccoli.

She walks through. The office is unheated and dusty, its windows almost opaque with grime. The only furniture is an elderly steel desk, with two takeaway cups of Costa coffee on it, and a pair of rust-scarred folding chairs.

"Eve, please."

"Richard Edwards, Mrs. Polastri. My apologies."

She shakes her head, bemused.

"It's Mrs. And you are?"

"Come in, take a seat."

"Let me save time. You are being held responsible for failing to prevent the murder of Viktor Kedrin at the hands of an unknown female. Your initial judgement was not to request Metropolitan Police protection for Kedrin, but you then changed your mind, and found this decision blocked. Correct?"

"I guessed milk but no sugar."

"And the cloak and dagger. Sorry for that, too."

"I've become aware of your situation at Thames House, Mrs. Polastri."

He nods, his gaze austere in the dim light of the window.

"Thank you, perfect." She takes a sip.

She recognises him, and is astounded. Former station chief in Moscow, now head of the Russia desk at MI6, he is a very senior figure indeed in the Intelligence world.

"Miss Polastri? Thank you for coming."

"My information, and you're going to have to take my word on this, is that this was not due to administrative inflexibility or departmental budget issues. Certain elements at Thames House, and indeed at Vauxhall Cross, were determined that Kedrin should be unprotected."

She stares at him. "You're saying that officers of the Security Services conspired to assist in his murder?"

"The short answer is that I don't know. But there has definitely been pressure brought to bear. Whether this is an issue of ideology, corruption, or what the Russians call kompromat -- essentially blackmail -- it's impossible to say, but there's no shortage of individuals and institutions who would have liked to see Kedrin silenced. What he offered was the blueprint of a new, fascist superstate, implacably hostile to the capitalist West. It wouldn't have come into being tomorrow, but look a little further downstream, and the prospects are grim."

"Something like that."

Eve nods. "Substantially, yes."

"But… why?"

"So you think those responsible might belong to some pro-Western, pro-democracy group?"

"Not necessarily. Could easily be another hard-right outfit, determined to do things their own way." He stares at the traffic on Tottenham Court Road. "I contacted the Russian foreign minister last week via… let's call it the old spies network. I promised him that as Kedrin was murdered on British soil, we would find his killer. He accepted this, but made it quite clear that until such time as we did so, a state of diplomatic hostility would exist between our respective nations."

He turns to face her. "Eve, I want you to go to Thames House tomorrow morning, and offer your resignation, which will be accepted. Then I want you to work for me. Not from Vauxhall Cross, but from this office, which we appear to own. You will receive an SIS executive grade salary, a deputy, and full tech-com support. Your mission, which you will prosecute by any means necessary, is to identify the killer of Victor Kedrin. You will discuss this with no one outside of your team, and you will answer only to me. Anything you need in the way of extra personnel -- watcher teams, armed backup -- you will clear through me, and only through me. In effect, you will operate as if in hostile territory. Moscow rules."

Eve's thoughts are ricocheting all over the place. "Why me?" she asks. "Surely you've got --"

"Thank you."

"I'll do it," she says. "I'll hunt her down. Whatever it takes."

"To be brutal, because you're the one person that I know not to be compromised. How far the rot spreads, I can't say. But I've looked pretty closely at your record, and my judgement is that you're equal to the task."

Richard Edwards nods. Holds out his hand. And Eve knows that nothing will ever be the same again.

"Don't thank me. This is going to be hard and dangerous. Whoever this shooter is -- and there are echoes of several high-profile international kills by a woman in the last couple of years -- she's dug in deep, and she's very, very well protected. If you take this on, you must do the same thing. Dig in deep." He looks around the bare, cold room. "It's going to be a long winter."

Eve stands there. She has the dizzying impression that the world has slowed. There's a moment of intense silence.