If Dennis Cradle is surprised to see Eve when she collects him from his house, he conceals it well. The car is an eight-year-old VW Golf from the MI6 vehicle pool, smelling of stale air-freshener, and Cradle takes his place in the passenger seat without a word. As they drive away Eve switches on the Radio 4 Today programme, and they both pretend to listen to it.

Cradle remains silent for the duration of the journey to Dever. Initially, Eve reads this as a desperate attempt to assert some sort of authority, given that when she worked at MI5 he was considerably her senior. And then a darker interpretation of his manner strikes her. He's not saying anything because he knows exactly what she's doing here, and so does the organisation he works for. In which case, how much else do they know about her? And for that matter, about Niko? At the thought that her husband might be the object of hostile surveillance, and possibly worse, Eve feels a twisting, agonising guilt. There is no way of avoiding the fact that she's brought this situation on herself. Richard would have understood if she had decided to step down after Simon Mortimer was murdered in Shanghai; indeed, he encouraged her to do so. But she can't, and won't, let go.

The traffic is heavy leaving London, but Eve is able to make up time on the motorway, and it's just after quarter to nine when she takes the slip road signposted "Works Access Only". The road leads through sparse woodland to a steel gateway set into a high chain-link fence topped with razor-wire. In front of the gate is a guardhouse, where an armed military police corporal checks Eve's security pass before nodding her through the gate towards the cluster of low, weather-stained brick buildings that comprise the former government research station. As Eve drives into the car park, she sees half a dozen tracksuited figures running laps of the fenced perimeter. Others, carrying automatic weapons, saunter between the dilapidated buildings.

In part, it's a desire for answers. Who is the unnamed woman who has carved such a bloody trail through the shadowlands of the intelligence world? Who are her employers, what do they want, and how have they achieved such terrifying power and reach? The mystery, and the woman at the heart of the mystery, speak to a part of Eve that she's never really explored. Could she herself ever be transformed into someone who acts as her target does? Who kills without hesitation or pity? And if so, what would it take?

"I'm assured not."

"Shall I be mother?" asks Cradle drily, approaching the trestle table.

At the reception block, Eve and Cradle are met by a trooper from E Squadron, the Special Forces unit based at the camp. Casting an eye at Eve's pass, he beckons them to follow him. The interview room is at the end of a strip-lit underground corridor. It's minimally furnished and there are no CCTV cameras in evidence. A trestle table holds an electric kettle, a half-full bottle of mineral water, two stained mugs, a packet of biscuits and a box holding tea bags and sachets of sugar and powdered milk. The room is colder than Eve would have liked, and the air-conditioning gives off a faint, shuddering whirr.

"Whatever," says Eve, seating herself in a dusty plastic chair. "I haven't got time to waste here, and neither have you."

"Are we observed? Overheard? Recorded?"

"I suppose that will have to do… Christ, these biscuits must be six months old."

"Ground rules," says Eve. "You lie, prevaricate or bugger me around, the deal's off."

"Do you understand what I just told you?"

"Mrs Polastri. Eve. I've been conducting tactical questioning sessions for over a decade. I know the rules."

"Fair enough." He pours the mineral water into the kettle. "Milk, one sugar?"

"Good. Let's start at the beginning, then. How were you approached?"

Cradle yawns, unhurriedly covering his mouth. "We were on holiday, about three years ago. A tennis camp, near Málaga. There was another couple there from Holland, and Penny and I started playing regularly with them. They told us that their names were Rem and Gaite Bakker, and that they came from Delft, where he was an IT consultant and she was a radiographer. In retrospect I doubt that any of that was the case, but I had no reason not to believe it at the time, and we became quasi-friends, in the way that you do on holiday. Going out for meals together, and so on. Anyway, one evening Penny and Gaite went with some of the other wives on a girls' night out -- flamenco, sangria, all that -- and Rem and I went to a bar in the town. We talked about sport for a bit, he was a big Federer fan, and then we got onto politics."

"I gave him the standard, non-specific Home Office line. And inevitably, for a time, we got stuck into the immigration question. He didn't push the politics, though. I think we ended the evening talking about wine, which he knew a lot about, and as far as I was concerned it was just one of those pleasant, setting-the-world-to-rights-type evenings that happen on holiday."

"I remember thinking, in an English kind of way, that it was slightly overstepping the mark. That going out for a drink on holiday was one thing, but pursuing the acquaintanceship afterwards quite another, even though we'd gone through the motions of swapping email addresses. At the same time I have to admit that the thought of drinking truly great Burgundy just once in my life was too good a chance to pass up, so I said I'd go."

"So what did you tell this man Rem that you did for a living?"

"And then?"

"And then, a month after we went back home, Rem emailed me. He was over in London for a couple of days, and he wanted me to meet a friend of his. The idea was that the three of us would go to a wine club in Pall Mall, where the friend was a member, and try out a couple of rare vintages. He mentioned, I recall, Richebourg and Echezeaux, which were quite some distance out of my orbit on a Thames House salary, even as a deputy head of section. Did you say you wanted milk and sugar?"

"Black's fine. So how did you feel about him getting back in contact like this?"

"A Russian, Sergei. A young guy, about thirty, incredibly polished. Brioni suit, flawless English, perfectly accented French to the sommelier, charming as the day is long. And on the table, unbelievably, three glasses and a bottle of DRC."

"Pretty much," says Cradle, handing her one of the mugs. "And when I got there, I can tell you, I was glad I went."

"In other words, they played you perfectly."

"And what's that, when it's at home?"

"Domaine de la Romanée-Conti. The finest, rarest and without question the most expensive red Burgundy in the world. This was a 1988, with a list price of around twelve K. I practically fainted."

"That was your price? The chance to drink some expensive wine?"

"So who was the friend?"

"Don't be judgemental, Eve, it doesn't suit you. And no, that wasn't my price. That was just the handshake. And good though the wine was, and when I say good I mean sublime, I didn't feel myself compromised in the slightest, and in the normal course of events I would've happily thanked Rem and Sergei, shaken hands and never seen either of them again."

"The conversation. Sergei, if that was really his name, had a grasp of global strategy that you rarely encounter outside the better think-tanks and the higher echelons of government. When someone like that dissects and lays out the issues, you listen."

"So what was abnormal about that evening?"

"After listening to him for a few minutes I had no doubt of that. Or that he and Rem were important players in the intelligence world. The whole thing was very fluent, and I was curious to see what the offer would be."

"It sounds as if he knew exactly who you were."

"Of some kind. But they didn't lead with the money, and… well, you can choose to believe this or not, but it wasn't about that. The money, I mean. It was about the idea."

"You knew there'd be an offer?"

"The idea," says Eve flatly. "You're telling me that this was nothing to do with apartments in the south of France, or twenty-something Serbian gym instructors sunning themselves on yachts, or anything like that. You're saying that this was about conviction."

"No idea."

"Are you sure? Tony Kent. Think."

"He was the fixer behind the scenes. He paid you, basically, though he tried very hard to cover his tracks."

"Whatever you say."

"That's how it looks to you, is it?"

"And you're telling me that you believed in this cause of theirs? Seriously?"

"So who's Tony Kent?"

"Eve, listen. Please. You know, and I know, that the world's going to hell. Europe's imploding, the United States is led by an imbecile, and the Islamic south is moving north, dressed in a suicide vest. The centre cannot hold. As things stand, we're fucked."

"Like I said, you can choose to believe me or not."

"That's how it is, period. Now you might say that the West's loss is the East's gain, and that while we tear ourselves apart they make hay. But long-term, that's not how it works. Sooner or later, our problems become their problems. The only way that we retain any kind of stability, the only way that we all survive, is if the major powers co-operate. I don't just mean through trade agreements or political alliances, I mean actively working as one to impose and protect our values."

"I'm completely sure. I was told nothing I didn't need to know. No one was giving out names, I promise you."

He leans forward on his chair. His eyes meet and hold hers. "Look, Eve. We're alone here. No one's watching, no one's listening, no one knows or gives a shit what we're talking about. So I'm asking you to see sense. You can be on the side of the future, or you can lock yourself into the burned-out wreck of the past."

"You were going to tell me about those values."

"I'll tell you what's been proven not to work. Multiculturalism, and lowest-common-denominator democracy. That's had its day. It's over."

"These values being, specifically?"

"And in its place?"

"A new world order."

"I don't consider myself a traitor. And as for assassins, what do you think E Squadron's for? Every system needs its armed wing, and yes, we have ours."

"So why did you kill Viktor Kedrin? I'd have thought his political philosophy was right up your street."

"It was. But Viktor was also a drunk with a taste for very young girls. Which would have got out, sooner or later, and tainted the message. This way he's a martyr, tragically slain for his beliefs. I don't know if you've been to Russia lately, but Viktor Kedrin is everywhere. Posters, newspapers, blogs… Dead, he's far more popular than he ever was when he was alive."

"Engineered by traitors and assassins?"

"Which woman?"

"I have no idea. You'll have to speak to someone from Housekeeping."

"Tell me the name of the woman."

"The assassin who killed Kedrin on my watch, and killed Simon Mortimer, and God knows how many others besides."

"And I told you I don't know." He regards her steadily. "I also suggest you put that thing away before you cause an accident. I'm worth a great deal more to you alive than dead. Imagine the explaining you'd have to do."

She lowers her arm, furious at herself. "And you'd do well to remember the conditions under which you're sitting here talking to me, rather than under arrest for treason. You're going to tell me the names of all your contacts, and how and when you communicated with them. You're going to tell me what services you performed for them, and what information you passed them. You're going to describe who paid you, and how. And you're going to give me the names of every single member of the Security Services, and indeed anyone else, who has betrayed his or her country to this organisation."

A second later, without conscious thought, Eve has unholstered her automatic pistol and is pointing it at Cradle's face. "I said don't fuck with me. What's her name?"

"Your husband called," he tells her. "Says you need to get back home, there's been a break-in."

"What?"

She nods, and fumbles for her phone. The call goes straight to Niko's message service, but moments later he calls her back. "I'm at the flat. The police are here."

"All pretty strange. Mrs Khan, over the road, saw a woman climbing out of our front room window -- completely brazen, apparently, not trying to hide what she was doing at all -- and dialled 999. First I knew of it was when a couple of uniformed cops came to the school and picked me up. Nothing's missing, as far as I can tell, but…"

"I'm afraid I don't have that information. Sorry."

"Wait here," she tells Cradle, and follows the trooper up to ground level, where a compact, moustached officer is waiting for her.

There's a peremptory knock at the door and the trooper who brought them to the interview room leans in. "Boss has a message for you, ma'am. Can you come up?"

"So what happened?"

"That's what it's called. The Twelve. Le Douze. Dvenadtsat."

"The Twelve."

Eve stares at him. "Did he say anything else? Is he OK?"

"Look, Eve. I'm not sure what your present status is, or exactly which department you now work for, but I do know that it wasn't very long ago that you were in a junior liaison post at Thames House, earning chicken-feed. Public service its own reward, and all that bollocks. And I'm betting things haven't greatly changed. Financially, at least."

Eve knows. She just knows. Minutes later, she's driving southwards on the A303, with Cradle in the passenger seat. She dislikes the physical closeness, and the faint but cloying smell of his aftershave, but she definitely doesn't want him lurking behind her.

"I'm empowered to make you an offer," he says, as they pass Micheldever service station.

"Any description?"

"Imagine, though. Suppose you had a few million banked, so that when the time was right, you and your husband could give up work and slip away to the sunshine. Spend the rest of your life travelling first class. No more cramped flats or crowded tubes. No more endless winters."

"Young, slim…"

"Just get back here, OK?"

"Shit!" Eve brakes hard to avoid a Porsche that has swerved into the slow lane to overtake her on the inside. "Nice driving, arsehole!"

"You make me an offer? Are you fucking kidding me?"

"I'm assuming the woman got away?"

"But what?"

"Yes."

"It will do, in the end. Because I know that you're smart enough to realise that you need me. That the ship of state isn't sinking, it's sunk."

"Worked brilliantly for you, didn't it?"

"Oh God, I don't believe this." A police motorcycle, blue lights flashing, is growing larger and larger in her rear-view mirror. Eve slows down, hoping that the motorcycle will race past, but it swings in front of her, and the uniformed officer indicates with a waving arm that she pull in on the hard shoulder.

"You seriously believe that?"

"Eve, what I'm suggesting isn't treasonable, it's common sense. If you really want to serve your country, join us and help create a new world. We're everywhere. We're legion. And we will reward you…"

Eve lowers the window. "Is there some problem?"

As Eve does so the officer halts in front of her, pulls the powerful BMW bike onto its stand, saunters over, and peers through the driver-side window.

"Can I see your licence please?" A woman's voice. The visor of her white helmet reflecting the sunlight.

"Oh, for heaven's sake." Slowly, not attempting to disguise her frustration, Eve climbs out of the car. Traffic races past, terrifyingly close.

"Out of the car, please. Both of you."

"Right away, please."

"Seriously? I'm travelling to London because there's been a break-in at my house. You're welcome to check with the Met. And I strongly suggest you take another look at that pass."

"Hands on the bonnet. Legs apart."

Eve hands her the licence, along with her Security Services pass.

"Turn round."

That not-quite-identifiable accent, unusual in a police officer. Doubt is beginning to enter Eve's mind now. Expert hands pat her down, take her phone, and unholster the Glock. She hears the faint click of the magazine release, and then feels the pistol replaced. This, Eve knows with sick certainty, is no police officer.

Eve does so. Notes the lean female form in the high-visibility jacket, leather trousers and boots. Watches as the woman's hands lift her visor to reveal a flat, ice-grey gaze. A gaze that she has encountered once before. On a busy street in Shanghai, the night that Simon Mortimer was found with his head all but hacked from his body.

"I see," says Eve, trying to steady herself.

"You," Eve says. She can hardly breathe. Her heart is slamming in her chest.

Cradle looks at Eve, smiles, and shrugs. "Sorry," he says. "I'm afraid you lose this round. We look after our own, you see."

"Don't be like that, Eve. Don't be bitter."

"Are you going to kill Cradle?"

"Me." She removes her helmet. Underneath it she's wearing a Lycra face-mask that conceals all her features except those frozen grey eyes. Lowering the helmet to the ground she beckons to Cradle, who walks over. "Let the VW's tyres down, Dennis, and put the car key in your pocket. Then wait over by the motorcycle."

"Please. Let's not talk about that. We meet so rarely." She raises her hand and touches a finger to Eve's face, and as she does so Eve is dumbfounded to see that she is wearing the bracelet that she lost in Shanghai.

"It is what you do, isn't it?"

The woman takes her by the upper arm, leads her away a few paces, and examines her features as if trying to commit them to memory. "I've missed you, Eve. Missed your face."

"Why? Do you think I should?"

"I wish I could say the same."

"Spoil things? You broke into my fucking house this morning, and you're worried that you'll spoil things?"

"That's… that's mine. Where did you get it?"

Eve stares at her, blank-faced. "You… watched me sleep?"

"You're taking him?" Eve nods at Cradle, who is loitering by the motorcycle, twenty paces away.

"From your room at the Sea Bird Hotel. I climbed in one night to watch you sleep, and I just couldn't resist it."

"You know my name but you're not going to tell me yours?"

"What was her name? What's your name?"

"You looked so adorable, with your hair all over the pillow. So vulnerable." She loops an errant tress behind Eve's ear. "You should take more care of yourself, though. You remind me of someone I used to know. The same pretty eyes, the same sad smile."

"Oh, Eve. I have so many names."

"It would spoil things."

"I wanted to leave you something. A surprise." She shakes the bracelet on her wrist. "In return for this. But now, although I'm really loving our chat, I have to go."

"I have to. But we must do this again, there's so much I want to ask you. So much I have to tell you. So à bientôt, Eve. See you soon."

As they fly along the country roads, the trees and hedgerows still vivid in the early autumn sunlight, Cradle feels a profound lightening of spirit. They've come for him, as they always promised they would if he was blown, and now they're going to take him somewhere safe. Somewhere the Twelve's word is the rule of law. It will mean never seeing his family again, but sometimes you have to make sacrifices. In the case of Penny, that sacrifice is not so arduous. And the kids, well, he's given them a first-class start in life. Fee-paying north London schools, skiing holidays in the Trois Vallées, godparents well-placed in the City.

He wasn't expecting a woman to come for him, but he certainly isn't complaining, given what he's seen of this one. She certainly put that Polastri bitch in her place. And what genius to send her in the guise of a traffic-cop.

They ride for almost an hour, before stopping by a bridge over a river outside the Surrey town of Weybridge. The woman pulls the BMW onto its stand, then removes her helmet and jacket, tugs off her face-mask, and shakes out her hair. Taking off his own, borrowed, helmet, Cradle stares at her appreciatively.

A path leads from the road down to the side of the River Wey. The water is dark olive, the current so slow that the surface looks still. The banks are shadowed by trees, and overgrown with cow-parsley. At intervals, narrowboats and barges lie motionless at anchor.

"Let's walk," she says, glancing at the BMW's satnav. "The rendezvous for the next stage of your journey is up this way."

He considers himself something of a connoisseur of the female form, and this one scores highly. The dark blonde hair sweaty, but nothing he can't work with. The eyes a bit frozen and weird, but that mouth suggesting whole realms of sexual possibility. The tits? Sweet as apples beneath the tight T-shirt. And what man didn't feel a stirring in his Calvins at the sight of a girl in leather trousers and biker boots? Dressed like that, she has to be up for it. And he is, effectively, a single man again.

"I can't tell you that."

"Perhaps, if we meet again…" he begins.

"Yes?"

"So where am I going?"

"Bite of dinner? Something like that?"

"Perhaps."

"This is the rendezvous," she says.

They continue along the sun-splashed path, passing no one, until arriving at a broad weir-pool fringed with bullrushes and flag-iris.

Cradle looks around him. The river, its waters moving smoothly towards the rushing weir, has the keen, indefinable smell of such places. Mud, vegetation and rot. There's a timelessness about the scene that reminds him of his childhood. Of The Wind in the Willows, of Ratty, Mole and Toad. And that chapter he never quite understood: "The Piper at the Gates of Dawn". Cradle is pondering this enigma when a police-issue baton, swung with extreme force, connects with the base of his skull. He pitches almost noiselessly into the river. His half-submerged body hangs there for a moment, and then, as Villanelle watches, begins its inexorable drift towards the crest of the weir, where it is immediately drawn deep underwater. She stands there, imagining his body turning and turning in the vortex, far beneath the glassy surface. And then she holsters the baton, and unhurriedly makes her way back along the path.

By the time Lance drops her off at her house, Eve is exhausted. She's also furious, apprehensive, and faintly nauseous from the nicotine smell of Lance's car. There's a horrendous conversation with Richard still to be had -- he's coming by the office at 6 p. m. -- but the most shaming admission that Eve has had to make is to herself. How easily, how effortlessly and contemptuously, she has been played. How naive she has been. How utterly unprofessional.

So she's in no mood for Niko's hostility when he lets her into the flat. "I rang you four and a half hours ago," he tells her, pale-faced with suppressed tension. "You said you'd be here by midday, and it's nearly three."

She should have known, from Cradle's bullish manner, that he had sounded some sort of alarm, and expected to be exfiltrated. Rather than congratulating herself on having uncovered his treachery, she should have been expecting precisely the sort of audacious manoeuvre that had been mounted against her. How could she have been so ill-prepared? And then there's that surreal encounter on the A303, which has left her shot through with emotions she can't begin to define.

Niko compresses his lips, and nods. "As I told you on the phone, Mrs Khan reported seeing a young woman climbing out of our window at about ten thirty this morning, and rang the police. Two police officers called round at the school, picked me up, and drove me here. They were obviously taking the whole thing quite seriously, because there was a forensics person waiting outside when we got back. Perhaps they've got our address on file because of your old job at MI5, who knows? Anyway, they went through the flat with me, room by room, and the forensics woman did her stuff on the door handles and the front room window and various other surfaces, looking for fingerprints, but she found nothing. She told me the intruder must have been wearing gloves. She'd undone the window lock, but nothing else had been disturbed, as far as I could see, and nothing taken."

She forces herself to breathe. "Look, I'm sorry, Niko, but explanations are going to have to wait. If you've had a bad day, trust me, I've had a worse one. Since we spoke I've had my car keys and my phone stolen, and I've spent an hour beside a busy main road, trying to wave down a car so that I could get help. And that's just the start of it. So just tell me, without getting angry, what's going on."

"So… do you have any idea who she might be?"

"Tell me the truth, Eve. Seriously, I need to know. I need you, just this once, not to lie."

"So how do they think the intruder got in?"

"Through the front door. They had a close look at the lock and they reckon she picked it. Which makes her a professional, not some teenager looking for phones and laptops."

"Niko, truthfully, I have absolutely no idea who this was. Nor is there any reason whatsoever to connect this with my work, or the investigation you were talking about. Do you know how many break-ins were reported in London last year? Almost sixty thousand. Sixty thousand. That means that statistically --"

"Fine, just chilling outside. They made a big impression on the cops, as you can imagine."

"Thelma and Louise?"

"Ages ago."

"Please, Eve, you know what I mean. Is this something to do with your work? Was this woman looking for something specific? Something…" His voice trails off, and then, as she watches, a darker suspicion takes hold. "Was this… that woman? The one you were after? Probably still are after? Because, if so…"

"They left, these cops?"

"I don't know any professional burglars, no."

She meets his stare calmly.

"Right."

He stares at the wall. "Maybe the police will --"

"Statistically." He closes his eyes. "Tell me about statistics, Eve."

"No, the police won't. Especially if she didn't take anything. They'll log it, and it'll go in the files. Now let me have a look round the place, and make sure nothing's missing."

"Niko, please. I'm sorry you think I lie to you, I'm sorry some burglar broke into our house, I'm sorry we don't have anything worth stealing. But this is just some random fucking London event, OK? There is no explanation. It just… happened."

"Oh, yes please. And if there's any of that cake left, I'm starving." Stepping behind him, she puts her arms around his waist and lays her head against his back. "I'm sorry, I've really had the most horrendous day. And this just makes it worse. So thank you for coping with the police and everything, I honestly don't think I could have managed."

He stands there, breathing audibly. Finally, slowly, he bows his head. "I'll make some tea."

Opening the back door, she smiles as Thelma and Louise come bounding towards her and nose inquisitively at her hands. They really are very hard to resist. On the far side of the wall bordering the tiny patio there's a drop of some twenty metres to the overground railway track. Its proximity to the line, the letting agent explained to them when they moved in, was the reason that the flat was cheaper than others in the area. Eve no longer hears the trains; their rattle and thrum has long been subsumed into the ambient noise that is London. Sometimes she sits out here and watches them, soothed by the ceaselessness of their coming and going.

"Go on."

"When did we last spend a weekday afternoon together?" Niko asks, handing her a cup of tea with a slice of cake balanced on the saucer. "It seems like for ever."

"About Russia." She takes a bite of cake.

"Have you ever heard of anything or anyone called the Twelve?"

"What poem?"

"You're right, it does," she says, staring out towards the dim, urban horizon. "Can I ask you something?"

"Someone at work today referred to an organisation called the Twelve. Some political group. Either Russian, or Russian-connected. I'd never heard of it."

"What about it?"

Eve feels a coldness at the back of her neck. "What's it about?"

"Dvenadtsat. The Twelve, by Aleksandr Blok. He was an early twentieth-century writer who believed in the sacred destiny of Russia. Pretty crackpot stuff. I read him at university, during my revolutionary poetry phase."

"Twelve Bolsheviks pursuing some mystical quest through the streets of Petrograd. At midnight, as far as I remember, and in a snowstorm. Why?"

"The poem, you mean?"

"That a group calling itself after Blok's midnight ramblers could be of almost any complexion from neo-communist to outright fascist. The name doesn't tell you much."

Niko shrugs. "Most educated Russians would know the poem. There's nostalgia for the Soviet era right across the political spectrum."

"So do you know where I could… Niko?"

"What do you mean?"

But Thelma and Louise are butting at his knees and bleating for his attention.

Tea in hand, Eve goes through the flat. It's a small place, and although it's crammed with stuff, mostly Niko's, it doesn't look like anything has been moved or stolen. She visits the bedroom last, checking under pillows and in drawers, and paying particular attention to her modest stock of jewellery. She's furious at the theft of her bracelet, and still can't begin to process the knowledge that a professional killer broke into her Shanghai hotel room while she slept. Imagining that woman staring at her with those flat, affectless eyes, and perhaps even touching her, makes her feel faint.

"You looked so adorable, with your hair all over the pillow…"

Eve opens the wardrobe and flips through her dresses, tops and skirts, sliding the hangers along one by one. And comes to a disbelieving halt. On a shelf with her belts, gloves and a straw hat from the previous summer is a small package wrapped in tissue paper, which she has definitely never seen before. After pulling on one of the pairs of gloves, she carefully lifts the package, weighs it in one hand, and unwraps it. A dove-grey box bearing the words Van Diest. Inside, on a pillow of grey velvet, an exquisite rose gold bracelet, set with twin diamonds at the clasp.

For several heartbeats, Eve stares. Then, twitching off her left glove, she slips her wrist into the bracelet and snaps the clasp into place. The fit is perfect, and for a moment, languidly extending her arm, she thrills to the look and the delicate weight of it. In the folds of tissue paper, its corner just visible, is a card. The note is handwritten.

Take care, Eve -- V

Eve stands there, the bracelet on her wrist, the card in her gloved hand, for a full minute. How should she interpret those words? As flirtatious concern, or outright threat? On impulse, she lowers her face to the card, and detects expensive, feminine scent. Her hand shaking, she replaces the card in the box, possessed by emotions she can't immediately identify. Fear, certainly, but an almost stifling excitement, too. The woman who chose that beautiful, feminine object and wrote that message is a murderer. A stone-cold professional assassin whose every word is a lie, and whose every action is calculated to unsettle and manipulate. To meet her gaze, as Eve did just hours ago, is to look into a heart-freezing void. No fear, no pity, no human warmth, only their absence.

How have the two of them locked themselves so inescapably into each other's lives? Could it be that, in some bizarre way, V is reaching out to her? Raising her arm, Eve touches the smooth gold to her cheek. What can this lovely, luxurious object have cost? Five thousand pounds? Six? God, she wanted it. Couldn't she perhaps just not say anything? Now that she's committed herself to a completely unprofessional course of action by unwrapping the thing in the first place, and quite possibly compromising forensic evidence, wouldn't it be easier to just… keep it?

Why is she so stirred by this lethally dangerous woman? Why do her words cut so deep? That cryptic V is no accident. It's a name, if only a partial one. A gift, like the bracelet. A gesture at once intimate and sensual and profoundly hostile. Ask and I will answer. Call and I will come for you.

Just metres away on the patio, talking enraptured nonsense to the goats -- the goats -- is the best and kindest man that Eve has ever known. The man into whose warm body, familiar but still mysterious, she moulds herself at night. The man whose unaccountable love for her has no horizon. The man to whom she now lies with such fluency that it's almost second nature.

With a flush of shame and regret, she removes the bracelet and places it back in its box. Fuck's sake. She's reacting precisely as her adversary wants her to. Falling for the most blindingly obvious temptation, and personalising the situation in a completely irrational fashion. How egotistical and delusional, to think that she, Eve, is the object of this V person's affection or desire. The woman is without doubt a narcissistic sociopath, and attempting to undermine Eve through passive-aggressive taunting. To think otherwise, even for an instant, flies in the face of everything Eve has ever learned as a criminologist and an intelligence officer. She takes a carrier bag from the floor of the wardrobe and stuffs the box, card and tissue inside with a gloved hand.

"Anything?" Niko calls out from the kitchen.

"No," she says. "Nothing."

On the Eurostar, no one takes much notice of the young woman in the black hoodie. Her hair is greasy, her pallor unhealthy, and there's something indefinably dirty about her. She's wearing scuffed black motorcycle boots, and her insolent posture suggests that she might use them on anyone rash enough to approach her. To the middle-aged couple sitting opposite her, working their way through the Daily Telegraph cryptic crossword, she's exactly the type of person that makes train travel so unpleasant. Unwashed. No consideration whatever for those around her. Forever on her phone.

"Give us another clue," the husband murmurs.

Villanelle, meanwhile, having disabled the location tracker on Eve's phone and read all her disappointingly boring texts and emails, is thumbing through her photographs. Here's Niko, the Polskiy asshole, in the kitchen. Here's an Eve selfie at the optician's, trying on new glasses (please, angel, not those frames). Here's another of Niko with the goats (and what the fuck is with those animals, anyway? Do they mean to eat them?). And then there's a whole series of celebrity portraits, which Villanelle guesses Eve has snapped from magazines so that she can show her hairdresser. Who's this one? Asma al-Assad? Seriously, sweetie, that look is so not you.

"Thirteen across: 'Eliminate a flock of crows'," says his wife, and they both frown.

"Where have you been?" Anne-Laure asks her. "I haven't seen you in an age."

Looking up, Villanelle sees from the high-rise blocks and graffiti-tagged walls that the train is entering the outer Parisian suburbs. Pocketing Eve's phone and taking out her own, she rings her friend Anne-Laure.

"The prêt-à-porter shows start tomorrow, and tonight some of the younger designers are having a party on my friend Margaux's boat at the Quai Voltaire. It'll be fun, everyone will be there. We could dress up and have dinner at Le Grand Véfour, just the two of us, and go on to the party afterwards."

The train is pulling into the Gare du Nord. Emboldened by their incipient arrival, the middle-aged couple look at Villanelle with frank dislike.

"Working. Travelling. Nothing interesting."

"That sounds nice. Margaux's cute."

"Run me through that again," says Richard Edwards. An intelligence officer of the old school, he is a vaguely patrician figure with thinning hair and a velvet-collared overcoat that has seen better days. "You say you were stopped by a person you thought was a police officer on a motorcycle."

"You tell me."

"Are you up for it?"

"So what are you doing this evening?"

"That crossword clue," she says to them. "'Eliminate a flock of crows'. Did you work out the answer?"

"It's 'murder'." She flutters her fingers. "Enjoy Paris."

"Er, no," the husband says. "We didn't, actually."

"Definitely."

"That's right," says Eve. "On the A303 near Micheldever. And I'm pretty sure it was a real police uniform and bike. The shoulder number and the plates both check out. They belong to a Road Policing Unit of the Hampshire Constabulary."

He, Eve, Billy and Lance are sitting in the Goodge Street office. A strip light casts a sickly glow. At intervals, there's a muted rumbling from the Underground station beneath them.

They look at each other. Eve's earlier exhilaration is now just a memory. What possessed me? she wonders. This whole situation is a catastrophe.

"Not easy to nick, I wouldn't have thought," says Billy, leaning back in the computer chair that almost seems part of him, and absently fingering his lip-piercing.

"Lance is right," says Richard. "If they've penetrated MI5, then they're certainly going to have people in the police."

"Unless you've got someone inside that particular force."

"OK, so this woman searches you, takes your phone and the ammunition clip from your Glock, and gets Dennis Cradle to pocket your car keys and deflate your tyres. You and she then have the conversation that you've described to me, in the course of which you notice that she's wearing a bracelet that belonged to you."

"I suppose there's no way of knowing where the bracelet was bought?"

"Obviously not."

"You then manage to wave down a car, borrow a phone, and ring Lance, who collects you in his car and drives you home. You get there at about 3 p. m., at which point you learn of the break-in at your house which took place at around 10.30 a. m."

"That's about the long and the short of it, yes."

"No. I already knew about that. My husband rang to tell me. That's why I was driving home early from Dever with Dennis Cradle."

"The bracelet was my mother's, and this woman told me she stole it from my hotel room in Shanghai."

"No, nothing disturbed or taken. But this Van Diest bracelet, and the note, had been placed in my wardrobe."

"And you never mentioned to her that you'd been to China."

"I've checked with the company," Eve says. "There are sixty-eight Van Diest boutiques and concessions worldwide. It could have come from any one of them. It could have been bought over the phone or online. I suppose it's a line of enquiry, but --"

"Of course, yes. But there was no sign of anything having been disturbed, or taken from your home?"

Richard nods. "So then she gives Cradle her spare crash-helmet, and drives him away on the motorcycle."

"None. The whole thing with the bracelets is very much her style. She'd have calculated that if she was seen climbing out of my flat, and the police were rung, there was a good chance that a message would get to me within an hour or so. She'd guess that I'd drive Cradle straight back to London, and that would give her enough time to get up to the A303 to intercept us. It'd be tight, but it could be done, especially on a police motorcycle."

"And there's absolutely no doubt in your mind that the woman who broke into your house, and the woman who stopped you on the A303 and abducted Cradle, were the same person?"

"OK, let's assume that you're right, and that this woman who signs herself V is the one we've been dealing with all along. The one who killed Kedrin, Simon Mortimer and the rest of them. Let's further assume that she works for the organisation that Cradle talked about, the one he said was called the Twelve. We still haven't answered either of the two key questions. One, how did she know that we were onto Cradle? And two, what has she done with him?"

"In answer to the first question, I got the strong impression that Cradle had contacted the Twelve himself. He probably had some kind of emergency number, and believed that if he was compromised he'd be pulled out, like an agent in the field. In answer to the second question, she's killed him. I've no doubt about that whatsoever. It's what she does."

"Which means --" Richard begins.

"I do. I rode Cradle far too hard in that phone call to the van. I never thought he'd let his people know we were onto him. What did he think they were going to do? Did he really believe he'd live happily ever after?"

"I don't accept that."

"Yes. We've got a senior MI5 officer dead, a serious amount of explaining to do, and no lead of any kind. We're back where we were post-Kedrin, and it's entirely my fault."

Without warning, the overhead strip light cuts out, plunging them all into dimness. Lance takes a broom from the stationery cupboard behind the printer, then taps the handle sharply against the fluorescent tube, which flickers for a moment and then comes back on again. No one comments.

"I listened to your conversation with Cradle. We all did. And you handled him fine. The truth is, he was in serious trouble with those people from the moment we identified him, however we played it."

"I'll handle them. Let them know about the south of France property and the boat and the rest of it. Say we're not sure who was paying Cradle off, but that someone was, big-time. Explain that we questioned him, which they'll find out sooner or later, and that he did a runner. That way, the whole thing becomes their problem. And when he turns up, which he will -- dead or alive but probably dead, as you say -- they'll shut down the story in the usual way."

"Niko would literally go ballistic. Please not that."

"So what about MI5?" Eve asks Richard.

"So we carry on?" asks Eve.

"We carry on. I'll get a forensics person I can trust onto that bracelet and the note. Also, I'm going to have people watching your flat round the clock until further notice, unless you and your husband would prefer to move into a safe house."

"I'm still on the Cradle money-trail," says Billy. "And that goes to some seriously weird places. I'm also in contact with GCHQ about the Twelve, and hoping that someone, somewhere, has let something slip. If Cradle knew that name, so do others."

"OK. For the time being not. What else have we got?"

The rodent features sharpen. "I might go and sniff around the Hampshire Constabulary HQ in Eastleigh. Buy pints for a few coppers. Ask about borrowed bikes and uniforms."

"Lance?"

"I just want to get something clear," Eve says, walking to the window and staring out at the traffic on Tottenham Court Road. "Is the purpose of this unit still to identify a professional assassin? Or are we now trying to acquire intelligence on what appears to be an international conspiracy? Because I'm beginning to sense mission-creep."

"First and foremost, I want our killer," says Richard. "Kedrin was killed on our turf and I need a scalp to give Moscow. Also, this woman killed Simon Mortimer, one of our own, and that I won't have. But it's becoming increasingly clear that if we want her, we're going to have to acquire some understanding of the organisation she works for. And the more we see and hear of them, the more formidable a force they appear. But there's got to be a way in. A tiny corner you can unpick. Like, for example, this woman's interest in you."

"You must admit, the situation's got honey-trap written all over it."

Eve looks at him wearily. "Please, whatever's on your mind, don't share it."

Lance grins horribly, and stares into space.

"Seriously, people," says Richard. "What's she saying with this bracelet? What's the message here?"

"That she's in control. That she can drop into my life any time she chooses. She's saying I've got your measure, and compared to me you're a loser. She's saying I can give you all the things you want -- the intimate, feminine, super-expensive things -- but can't have. It's a woman-to-woman thing."

"Lance, I'm sure you're a great field agent, but you're a seriously tragic human being."

"You know what they say, Eve. Old dogs. New tricks."

"That's an understatement," says Eve. "But I've been watching her, too. She's been getting more and more reckless, especially in her dealings with me. That motorcycle cop caper, for example. Somewhere along the line she's going to go too far. And then we'll have her."

"Manipulative lady," murmurs Billy knowledgeably, hunching into his Megadeth hoodie.

Lance nods at the carrier bag holding the bracelet. "Maybe we don't really need to go out looking for her. Perhaps, if we just sit tight, she'll come to us."

Eve glances at Lance. He looks sharp and alert, like a ferret about to be slipped into a rabbit-hole.

Richard nods. "I don't like it, but I'm afraid you're right. That said, I think we need to acknowledge that we've turned a dangerous corner here. So full counter-surveillance measures, please. Remember your tradecraft. Eve and Billy, listen to Lance and be guided by him. If he tells you that a situation smells bad, you walk away."

"It's difficult. I got a split-second glance at someone I thought was her in Shanghai, and today she had this Lycra mask on under her helmet so that I could only see her eyes. But I could try."

"Meanwhile, Eve, I'll have a word with the CO at Dever. Ask him to set up a detail to watch your flat. You probably won't see much of them, but they'll be there if you need them. Can we get a photofit of this V woman?"

"Excellent. We're going to watch, and we're going to wait, and when she comes, we're going to be ready."