"You don't often see that."

Ruiz is hungry. We go looking for a cafe that does an all-day breakfast.

The sun is out and pigeons are fighting over crumbs on the pavement, beating their wings in a desperate dance. The waitress has a dreamy stare, loose hair escaping from a clip. Ruiz orders a full English with mushrooms, cooked tomato and baked beans.

"Wholegrain toast," he tells her. "My doctor wants me to eat healthier."

She doesn't smile. Ruiz polishes his knife and fork with a paper napkin.

"I did come across one detail-Augie Shaw must have known Natasha McBain."

"Why?"

"When the Heymans moved into the farmhouse, Augie was already mowing the lawns. He worked for the McBains."

"What about his old man?"

"I can't find a link, but Drury has a dozen officers looking for one."

"I still don't think Augie Shaw kidnapped those girls."

"Maybe you're right. Maybe you're thinking nice thoughts because your new girlfriend is his therapist." A small smile tugs at Ruiz's lips. "How was your date last night?"

"None of your business."

"That sounds promising."

He grins and jiggles a tea bag in boiling water.

"You'll be pleased to know that I too can flirt. I chatted up a very nice middle-aged divorcee in the front office of the County Court."

"The reason being?"

"I got a peek at the court transcripts for Aiden Foster's trial. The jury found him guilty of GBH with intent and the judge gave him seven years with a non-parole of four."

"Where is he now?"

"Her Majesty's Prison, Bullingdon."

"What about Callum Loach?"

"He still lives locally."

Ruiz reaches into his jacket pocket.

"I took the opportunity to peruse copies of the local rag at the library. Came up with this."

He hands me a pile of photocopied stories from the Oxford Mail, most of them concerning the trial. One clipping has a photograph of Natasha at the courthouse, being escorted through an angry crowd. The shutter has captured the moment when she flinches under the abuse and a faceless security guard pushes someone aside.

"They blamed her for what happened," says Ruiz, whose afternoon breakfast has arrived. He eats like a condemned man, with his elbows either side of his plate.

In the meantime, I read the articles. The last of them reports that Callum Loach has been selected in the British Paralympic Team. A photo shows him sitting in his wheelchair nursing a basketball.

Ruiz pushes his plate away. Belching quietly. "Being crippled is a powerful sort of motive... so is being sent to prison. I doubt if Aiden Foster shed many tears when Natasha McBain went missing."

"Maybe we should ask him," I reply.

"I'm way ahead of you." Ruiz pulls a ten quid note from his wallet and slides it under the teapot. "I booked us a visit. Visiting hours end at 4:30."

HMP Bullingdon is eighteen miles north-east of Oxford on the southern outskirts of Bicester. A category C training prison, it houses inmates who fall somewhere between serial killers (high security) and disgraced Cabinet ministers (open prison).

Wives and girlfriends have already started to gather at the visitors' center. Some of them have children, who fidget and fight, wanting to be somewhere else. Once inside we are searched, ID'd and have our belongings confiscated and put into lockers. Gifts are vetted in advance. Anyone wearing clothes too similar to prison garb is asked to change.

The formalities over, we are escorted to a large annex, which has fixed tables and chairs. Visitors must stay outside until the prisoners are brought from their cells. Dockets are presented and the doors opened. Visitors and prisoners are kept apart. Knees cannot touch or lips meet. Hands can be held and children lifted over the divide. Some kids are fine. Others are howling. Some don't leave the safety of their mothers' skirts, peeking out at the stranger sitting opposite.

Aiden Foster is twenty-three now, but looks younger. His pale blond hair is gelled into peaks like a seismic chart and he sits with his legs splayed as though he has weights hanging from his t.e.s.t.i.c.l.es. He's a boy playing a man, trying to survive in a place where men who look like boys get turned into women.

He gazes around the room, expecting to see someone else. Then his forehead creases. Mentally, the floor seems to tilt up and away from him.

He slouches loosely, rocking slightly. I notice the bruises on his neck and the shadows beneath his eyes. He has done it hard. Parole is coming.

Ruiz pulls a paper bag from his pocket. Inside are two packets of cigarettes and chewing gum. Aiden peers into the bag as though examining his school lunch. He stacks the cigarettes on the table with the gum on top.

I introduce myself and Ruiz does the same. Aiden doesn't react. He's trying to give the impression of being completely at ease. A small silver crucifix swings on a chain around his neck.

"We want to talk to you about Natasha McBain," I say.

"Has she turned up dead?"

"What makes you say that?"

"Why else would you be here?" He smiles.

"You don't seem very upset, Aiden."

"Oh, don't worry, I'm crying on the inside."

Again he smiles. Ruiz folds his arms, unimpressed. He's met a lot of smart-mouthed punk kids and has never lost his desire to punch them.

Certain people don't seem to match their voices and Aiden Foster is one of them. His tone is pitched too high, but he tries to roughen it up by adopting a growl. I've read his police file and the trial transcripts of his evidence. I know his type. He's a bully when he can be and a victim when it suits him. I knew somebody like him once, a lad called Martin Payne who made my life a misery at boarding school. Martin joined the army when he graduated. He fought in Bosnia and Kuwait, winning the Queen's Gallantry Medal. Despite these heroics, I always considered Martin to be most at risk of being struck by a random thought. As it happened, I was right. After drinking fourteen pints he bet a friend that he could jump between two platforms on the London Underground-a leap that would have made Bob Beamon proud. Martin landed six feet short and perished on the live rail. Undone by idiocy.

Aiden leans back in his chair, scratching his groin. I point to his crucifix.

"Does G.o.d help you sleep at night or does he play well with the parole board?"

"The priest here has been good to me."

"Let's talk about Natasha."

"What happened to her?"

"She fell through the ice on a frozen lake."

"In London?"

There is a pause, before Ruiz asks the obvious question. "What makes you think she was in London?"

Aiden hesitates, preparing to lie.

"Had you heard from her?" I ask.

"No."

"Why then?"

There is another long silence. Ruiz speaks first. "Let me give you some free advice, Aiden, since you've still got six months to go. Most of the cons in here are uneducated, violent, washed-up drug addicts and habitual criminals. They know how to work the system... to survive. But you, Aiden, you're a fish. You're too young and pretty for a place like this. I bet the wolves have been sniffing around, waiting to introduce you to a little prison romance."

"No f.u.c.king way, man."

Something drops with a loud bang on the far side of the room and Aiden spins around as though shot. After a beat of silence, conversations begin again. Aiden tries to shrug it off but he's less sure of himself.

"Shower-time must be a nightmare," says Ruiz. "What do you do? If you fight them they punish you. You get shanked in the breakfast queue or lighter fuel thrown on your bed while you're sleeping. Are you getting much sleep, Aiden? I wouldn't be. I'd keep my back to every wall."

Aiden's eyes are wide.

"Or maybe you've found yourself a benefactor, someone who looks after you. What do you give him in return? Are you bending over for someone, Aiden? Or maybe you're muling drugs or lining up other fish?"

"You got it all wrong."

"I wonder what your mates are going to think when they hear you're somebody's prison b.i.t.c.h."

"No way, man! I'm n.o.body's b.i.t.c.h."

"That sort of rumor is hard to shake. Girls won't treat you the same way. They'll want you to take an Aids test just to look at them."

Aiden's eyes are filming over. "This is bulls.h.i.t!"

"I'm not telling you anything you don't know," says Ruiz. "Maybe it doesn't matter what your mates think. So what if they tell stories about you behind your back-about how some hare-lipped, flat-nosed con found you alone in the shower and uttered sweet nothings in your ear."

"That didn't f.u.c.king happen."

"I believe you, truly I do." Ruiz looks at me. "I don't know how these rumors start."

The silence lasts a dozen heartbeats.

"She sent me a letter," says Aiden.

"Who?" I ask.

"Tash."

"When?"

"A few months after she went missing." He squints at something on the ceiling. "She said she and Piper were in London. They were living in a squat and she was working for some guy who ran a place in Soho."

I look at Ruiz.

"Why did she write to you?"

"She said she was sorry."

"Sorry for what?"

"What do you f.u.c.king think?"

"Do you still have the letter?"

"Oh, yeah, I put it in my sc.r.a.pbook with my pressed flowers and needlework."

Aiden thinks that's funny. He wants an audience.

"Did you write back?"

"Why would I write to her? She put me in here. She put Callum Loach in a wheelchair. If it weren't for that little p.r.i.c.k-tease, none of this would have happened."

I can see Ruiz's shoulders flexing beneath his shirt. It isn't so much Aiden's whining that he dislikes, but his c.o.c.ky self-importance and how he wants to blame his own immeasurable stupidity on a schoolgirl because the alternative requires too much self-a.n.a.lysis and accountability.

"Why didn't you tell anyone about the letter?" I ask "Why should I? n.o.body did me any favors."

Taking a photograph from my jacket pocket, I place it on the table between his elbows. The image is from the post-mortem. Natasha's thin body laid out on the stainless steel bench, swollen and exposed, her eyes blank. Aiden is staring at me, unwilling to look. Slowly he lowers his gaze. Hesitates. Recovers.

"She's not so pretty now," he says, turning his face away from the photograph.

"You still think she got what was coming to her?" asks Ruiz.

Aiden smiles ruefully, showing all the compa.s.sion of a shark loose in a colony of seals.

"Been going to church while I been in here. Learned a few things. It's like the Bible says: 'Whatsoever a man soweth, that shall he also reap.' Man, woman, same difference. She got what she deserved."

As we leave the prison, Ruiz takes a boiled sweet from his tin and sucks it hard as though wanting to get a bad taste from his mouth.

"You know how most people in prison deserve to be there."

"Yeah."

"Some deserve it more than others."