Paul tapped the piece of paper. 'A few days before he...before the fire, he wrote to me. He mentioned your name.'

'And you've kept the letter all this time?'

'I've kept every souvenir of Stephen I could. But this letter I would have kept it anyway.'

'Why?'

He handed it to her. 'Read it and you'll understand.'

She hesitated before taking the piece of paper from him, and as it touched her fingertips she felt a thrill, a shiver, as if the ghost she thought she'd seen earlier had touched her.

CHAPTER 5.

She couldn't hear the clatter and murmur of the other diners any more. There was a wall of silence around her and Paul. The words on the page were all she was aware of. She recognised Stephen's handwriting. Before seeing it again she would never have been able to describe it, but as soon as it was there before her she knew those looping Ls, that tight, messy scrawl. A doctor's handwriting. They'd joked about it more than once.

The letter covered two sides of A4. She read through the first section quickly. Stephen started with a few unremarkable statements and observations the weather, the recent end of the World Cup, hope you were able to watch it, etc; what did that mean? and then the tone of the letter changed suddenly. The writing got more uneven, even more messy. It looked like it was written in a rush. There were mis-spellings, crossings out. So unlike the Stephen she knew.

Stuck in his flat one day, when he was at work, she had unearthed an old notebook from the back of his bookcase. In the notebook were poems, a couple of fragments from stories that he'd started writing, observations about places he'd been. It was beautifully written, with immaculate spelling and grammar. She never told him she'd found the notebook in case he was embarra.s.sed. He might, she feared, even be angry that she'd been snooping around. Then there were the notes he wrote her; cards that went with little gifts he'd bring home to her. He was careful and always accurate. This letter, with its mistakes and heavy pencil marks must have been written when drunk. Or under extreme stress.

Towards the end of the letter, the following pa.s.sage screamed out at her: I met a girl, her name's Kate. We've had to keep our relationship secret from the people here, but I don't think we're the only ones with secrets. _______________ I hope you meet her some day. If you do, and I'm not there, tell her I loved her. Tell her she was right. And tell her to forgive me.

Between the sentence that ended with 'secrets' and the start of the sentence that started 'I hope' were two lines that had been crossed out with thick black pen, obscuring all but the tips of a few tall letters and the tails of some others.

'Are you okay?' Paul asked, touching her wrist.

She s.n.a.t.c.hed her hand away as if his fingers were red hot then looked up, dazzled, unable to speak, to answer his question. Am I okay? No.

She stared at the letter again, reading it over like someone who's just received a letter telling them that sorry, the blood test result was positive, you failed the exam, you didn't get the job you so badly wanted, I don't love you any more. '"Tell her she was right."' She read the sentence aloud. 'Right about what?'

Paul raised an eyebrow. 'I was hoping you'd be able to tell me that.'

'And what does he want me to forgive him for?'

'You don't know?'

She screwed her face up, tapped her temples with the flat of her hand, perhaps hoping to knock the memories loose. Here was that thick fog again, descending over her mind, obscuring the past.

Paul said, 'You know something? I've kept this letter for years. I must have read it a hundred times. And every time, I asked myself what Stephen was talking about. What were the secrets? Who was this girl Kate and what was she right about? After Stephen died I became obsessed with finding out what he was talking about. I mean, it was obvious to me that he wasn't feeling himself when he wrote this letter. He was normally so calm and rational. Not unemotional, but with his head screwed on, you know what I mean?'

Kate did know.

'Who was this Kate person, I wondered? What had she done to make him like this, and what had he done to her, that she had to forgive? I asked Mum and Dad if they know anything about you, but they said they'd hardly heard from Stephen in the months before he died. I spoke to the couple of close friends he had, but they didn't know anything either. You were a mystery woman. n.o.body knew anything about you. This letter was the only proof that you existed. I puzzled over it for ages and then I made myself forget about it I had to in order to be able to get on with my life. But I always hoped that one day I might find this Kate, and that she'd be able to tell me what she was right about.'

Kate's voice trembled. 'I don't know. I don't remember.'

'Can't you try? Think back?'

'You don't understand.'

She explained to him about how patchy her memory was. 'It's so frustrating. I can remember some stuff incredibly clearly, but then there are these holes. I hardly remember anything about my second stay at the Centre, which was when it burned down.'

'You stayed there twice?'

'Yes. It's... well, maybe I'll explain why another time. This letter must have been written during my second stay. Yes, the dates add up. So whatever I was right about, it's something that must have happened during that second stay.'

'Could it just be something to do with your relationship? Maybe he's saying you were right about, I don't know, that you could make it work, while he was doubtful. Something like that?'

'No. It can't be. What about this stuff about secrets?' She was quiet for a few seconds, though the bubble around them remained, sealing out the clatter and clank of the other diners. 'You're going to think I'm crazy, but although I can't remember the details, I do know that there was something, something we couldn't agree on. Something to do with the Centre itself, or Stephen's job. I can almost see it. Almost taste it. But it's like...' She paused.

'What?'

She looked into his eyes. 'I'm scared. Scared of whatever this truth is. I feel like the heroine in a horror movie, standing outside the door of the big creepy house, grasping the handle, knowing that when I pull open the door I'll finally see what the monster looks like. But I don't want to see.'.'

Paul leaned forward. 'In the films, the girl always goes into the creepy house.'

'I know. But my brain won't let me.'

She sipped her beer. Her heart was still pounding in her ears, but the initial shock had faded a little and the cool scientist inside her had stepped forward. Here was a problem. How was she going to solve it?

She shook her head and sighed. 'I'm really jetlagged. I'll be able to think about it more clearly tomorrow. Do you mind if we leave now?'

'Where are you staying?' he asked.

She told him the name of her hotel.

'That's on my way. Let's take a taxi and I'll drop you off there.'

The next few minutes the walk to find a cab, the taxi ride pa.s.sed in a blur. When the taxi pulled up outside the hotel, Kate said, 'I'm really sorry that I can't answer your questions about the letter.'

'Hmm.' He appeared to have fallen intoa slight bad mood.

'It's not something I can help I wish I could remember.'

He didn't reply.

Kate pushed open the car door and climbed out, then walked quickly into the hotel, head down, through the revolving doors and towards the lift. She didn't have the energy to talk about the holes in her memory again, to justify herself to this guy she'd just met. She felt emotionally drained. She didn't want to have to think about anything else until tomorrow. All she wanted was to see Jack, to give him a cuddle before going to bed.

The taxi pulled away and headed around the hotel's circular forecourt, back towards the main road. Paul sat back in his seat, trying to process everything.

He couldn't believe that she had forgotten almost everything from that summer. G.o.d, it was frustrating. But then a stab of guilt hit him and he regretted the way he'd acted at the end of their encounter. He wouldn't be surprised if she didn't want to talk to him any more. And that would be terrible not only because it meant that this link to his brother was lost, but also because... well, he liked her.

'Stop the car, I need to get out.'

The driver glared back at him. 'You what?'

Paul thrust a ten pound note at him. 'Sorry. Changed my mind.'

He needed to talk to Kate again, to apologise. And maybe he could help her recover her memories, find out what it was that had happened that summer. This fire the official story was that it was an unfortunate accident, but what if that was a smokescreen? Bad choice of words, he thought to himself, grimacing. It had always seemed like a weird coincidence that Stephen had written this strange, emotional letter a few days before he died. Before, he had never had any way of going about finding out the truth. But now he'd found Kate, there was surely chance. He would go after the truth, for his brother's sake. To make amends for all the times he'd wronged him in the past. He cringed at the corny sentiment but it was true.

The lift doors pinged open and Kate made her way towards her room. She glanced at her watch. Nine o'clock - Jack should be asleep by now. The babysitter would probably be watching TV and would be surprised to see Kate back so early. She might raise a questioning eyebrow, wonder what had gone wrong. Maybe this overprotective parent couldn't bear to be away from her child for more than a couple of hours.

Kate took her keycard out of her wallet and swiped it in the lock. She pushed the door open.

The room was empty.

The babysitter, and Jack, were gone.

CHAPTER 6.

John Sampson glanced at the LED clock on the dashboard. 22:02. He'd been parked outside the McDonald-Taylor Research Inst.i.tute, on the outskirts of Oxford, for hours now. This part of Oxford was industrial and grey out of sight of the dreaming spires, but still connected to the university. Here, research was carried out in anonymous, flat buildings. Tourists didn't wander round this part of town gaping with awe, buying postcards and photographing one another in front of places they'd looked up in their guidebooks and found their way to. n.o.body looked twice at these buildings except for a few animal rights protestors. And it was those protestors who were responsible for making Sampson wait.

They were hanging around by the fence. A couple of middle-aged women; a younger woman, quite attractive in a sallow vegan way; and a bloke with a beard. Sampson had driven by earlier that day and seen the same group, plus a half-dozen others. Now only the hardcore remained. They carried placards that said STOP THE CRUELTY. Some featured grim pictures of monkeys with the word TORTURED above them. Sampson wondered what they'd think if they saw the things he'd seen a few days ago: the sick women imprisoned in tiny rooms; their blank despairing faces, shivering and whimpering. Would the protestors be as upset at the sight of cruelty to people? The question genuinely interested him. He wondered idly if these bleeding hearts would be able to teach him how to feel.

He took a long drag of his cigarette then crushed it to death in the car's pull-out ashtray. He didn't have time to think about that s.h.i.t right now. He had a job to do. And the f.u.c.king protestors were stopping him from doing it.

How long were they going to be? Beyond them, a single light was burning in the window of the inst.i.tute. Only one car remained parked in the staff car park.

The car belonged to Dr David Twigger, a scientist specialising in the study of viruses in animals. The protestors were outside because of the macaque monkeys and rats he used in his experiments. He argued that although he wished there was an alternative, using the animals was essential. He pointed out that the research carried out here was on diseases that affected animals not humans. They were trying to save animals, stop the viruses that affected pets, farm animals and wild creatures. The protestors argued that this was all very well, but why should some animals suffer so that others might be saved in the future? They also stated their belief that the only reason so much effort was put into studying these diseases was because scientists were worried they may spread to humans. Avian, or bird, flu was a prime example.

It was a moral maze Sampson was glad he had no morals and in actual fact the inst.i.tute did not attract much in the way of protests, unlike Huntingdon Life Sciences and other controversial places where the scientists and staff were threatened daily. The protests here were low-key and mild-mannered, carried out by a small bunch of locals.

Ignoring the protests, Dr Twigger worked until after dark, dedicated to his research. All the other staff had gone home and now it was just Dr Twigger and a couple of security guards. The building was surrounded by CCTV cameras and barbed wire, but because this lab concentrated on animal diseases and didn't store viruses that could harm humans and because of the low-level protests, security was not too tight, especially compared to some of the research facilities Sampson was familiar with. The protestors waited outside so they could scream abuse at Twigger as he drove home, possibly pelting his car with eggs for good measure, but no-one had ever physically attacked him or the building.

Tonight it looked as if Twigger wasn't going to come out. Not until the early hours anyway. Sampson watched the little group of protestors gather in a huddle, debating what to do next. From their body language it looked like the younger woman wanted to stay, but the others, especially Beardy, wanted to go home to their beds and the sleep of the righteous.

The majority won the argument and they shuffled away, taking their placards with them.

Sampson watched them go. At the corner of the street, they parted, the three older members of the group heading one way while the young woman went the other. For a moment he considered following her. He could grab her and lock her in the boot of his car until later. See if she could teach him something.

But he didn't have time. Twigger might come out while he was away, meaning Sampson would have to come back tomorrow. That wasn't going to happen. He wanted to get this over with tonight.

He watched the sallow vegan woman walk away. She was probably a student at the university. She would never know what a lucky escape she'd just had.

He opened the glove compartment, grabbed a balaclava and pulled it over his head. On the front of the balaclava were three letters: ALF. Everyone would think the protestors had suddenly decided to step up their efforts. Next, he put on a pair of black leather gloves, then opened the car door, got out and walked towards the fence.

On the way, he spotted some leaflets that the protestors had dropped. He picked one up and studied it. A cat stared out at him the most miserable cat he'd ever seen and the text below detailed the experiments that had been carried out on this cat and many others like it. 'Tortured in the name of science.' Sampson shook his head. These people didn't know the true meaning of torture. He could have taught the vegan girl if he'd had time, but now it was too late. The leaflet would come in handy, though. He folded it and stuck it in his back pocket.

Climbing the fence was easy for him. At the top he used a pair of cutters to snip through the barbed wire, then dropped gently onto the gra.s.s on the other side. He was thirty yards from the building. Now things would have to happen at speed. He took a deep breath. This was what he was good at.

A camera swivelled towards him as he broke into a jog towards the building. He knew the camera would record the letters on the balaclava. He knew the security guards employed by a private security firm, probably ex-police or ex-army, dulled by too many nights sat staring at screens on which nothing ever happened would panic and come out to meet him before calling for back-up. And even if they did call for back-up, Sampson would be in and out before they arrived.

He was right. The outside lights came on and the door was flung open. Two guards came running out, one with a crewcut, the other with short blond hair. The guard with the crewcut came towards him first, shouting 'Stop' as he ran. But in the harsh light Sampson saw confusion on the guard's face. He didn't understand why the guy in the balaclava was still running towards him in a straight line. Charging him. As Crewcut stopped and raised his gun, Sampson, without stopping, unsheathed and threw the knife he had just pulled out of his pocket. It spun in the air before landing deep in the guard's throat.

Crewcut dropped to the gra.s.s. A few steps behind, the blond guard saw his colleague fall, and stumbled to a halt. He raised his gun and fired, but Sampson had antic.i.p.ated this and veered to the left, the bullet cracking past him. Before the guard could fire another shot, Sampson was upon him.

He grabbed the guard's arm at the elbow and wrist and, raising his thigh, pushed his forearm swiftly down and snapped it. The guard choked on his own scream. Sampson took hold of the sides of the man's head and, with a single rapid motion, twisted, breaking his neck.

He stepped over the body and ran into the building through the door the inept security guards had left open, looked left and right to get his bearings, and ran towards the laboratory where Dr Twigger's light burned bright.

Sampson kicked open the lab door and found Dr Twigger waiting for him. The scientist stood at the far end of the laboratory, holding a metal bar. Sampson imagined the doctor probably kept this bar with him for security. What a waste of time. Behind him stood a row of six cages, each containing a macaque monkey. The brown-furred monkeys stared at him implacably from behind the bars. Between Sampson and the doctor was a bench bearing lab equipment: high-powered microscopes, a computer, test tubes, a jumble of flasks and dishes and the other paraphernalia of lab life. A pair of rubber gloves lay inside-out on the bench, as if they'd just been removed hurriedly.

Dr Twigger was a thin man in his late forties with hair that needed cutting. He looked like a frightened man who was desperate not to show that fear.

'Get out,' he said shakily, holding up the bar.

Sampson walked up to him and punched him in the face before the doctor could swing the metal bar, which he took hold of and wrenched from Twigger's grip. He threw it across the lab, the loud clanging making the monkeys jump and screech. They leapt about their cages, baring their teeth. Sampson glanced at them.

Twigger pulled himself upright. Blood trickled from his left nostril. He wiped it on the sleeve of his white coat.

'If you're planning to free these animals you're making a big mistake. They're sick and will attack humans. A monkey in that condition can do a lot of damage.'

Sampson ignored him. He walked over to the computer and pressed a key on the keyboard, keeping one eye on the doctor. He examined the figures on the screen, although they made no sense to him, then crouched down and unplugged the hard drive.

'Where are the backups?' he said.

'Backups? There aren't any.'

Sampson put the hard drive down on the bench and walked towards Twigger, who took a step back towards the cages. The monkeys leapt forward in their cages, hissing.

'Where are the backups?' he repeated.

'There aren't any...'

Sampson grabbed the doctor and turned him round, clutching the back of his neck. With his free hand he opened the door of the closest cage and pushed the doctor's head inside. Dr Twigger knew not to cry out. Sampson felt him tremble.

The monkey sat on the floor of the cage, eyeing the doctor's scalp and baring its sharp teeth.

Sampson said, 'So they can do a lot of damage?'

The doctor spoke in a whisper. 'Yes. Please.'

'I can't hear you.'

'Please.'

He pushed Twigger's head in further, glad of the leather gloves. The other monkeys were clinging to the bars of their cages, watching, waiting. If monkeys could make plans, dream of revenge, then surely they'd dreamt of getting revenge on this man who caged them and made them sick.