The door slammed open-Cassie jumped about a mile; Rosalind didn't move, didn't even take her eyes off Cassie's face-and O'Kelly, foreshortened to a blob by the camera angle but instantly recognizable by his spidery comb-over, leaned into the room. "Maddox," he said curtly. "A word."

O'Kelly, as I walked Damien out: in the observation room, rocking back and forth on his heels, staring impatiently through the glass. I couldn't watch any more. I fumbled with the remote, hit Stop and stared blindly at the vibrating blue square.

"Cassie," I said, after a very long time.

"He asked me if it was true," she said, as evenly as if she were reading out a report. "I said that it wasn't, and that if it were you would hardly have told her."

"I didn't," I said. It seemed important that she should know this. "I didn't. I told her that two of my friends disappeared when we were little-so she'd realize I understood what she was going through. I never thought she'd know about Peter and Jamie and put two and two together. It never occurred to me."

Cassie waited for me to finish. "He accused me of covering for you," she said, when I stopped talking, "and added that he should have split us up a long time ago. He said he was going to check your prints against the ones from the old case-even if he had to drag a print tech out of bed to do it, even if it took all night. If the prints matched, he said, we would both be lucky to keep our jobs. He told me to send Rosalind home. I handed her over to Sweeney and started ringing you."

Somewhere at the back of my head I heard a click, tiny and irrevocable. Memory magnifies it to a wrenching, echoing crack, but the truth is that it was the very smallness that made it so terrible. We sat there like that, not speaking, for a long time. The wind whipped spatters of rain against the window. Once I heard Cassie take a deep breath, and I thought she might be crying, but when I looked up there were no tears on her face; it was pale and quiet and very, very sad.

23

We were still sitting there like that when Sam got in. "What's the story?" he said, rubbing rain out of his hair and switching on the lights.

Cassie stirred, lifted her head. "O'Kelly wants you and me to have another go at finding out Damien's motive. Uniforms are bringing him over."

"Grand," Sam said, "see if a new face shakes him up a bit," but he had taken us both in with one quick glance and I wondered how much he was guessing; wondered, for the first time, how much he had known all along and simply left alone.

He pulled over a chair and sat down next to Cassie, and they started discussing how to go at Damien. They had never interrogated anyone together before; their voices were tentative, earnest, deferring to each other and rising into open-ended little question marks: Do you think we should…? What if we…? Cassie switched the tapes in the VCR again, played Sam bits of last night's interview. The fax machine made a series of demented, cartoonish noises and spat out Damien's mobile-phone records, and they bent over the pages with a highlighter pen, murmuring.

When they finally left-Sam nodding to me, briefly, over his shoulder-I waited in the empty incident room until I was sure they must have started the interrogation, and then I went looking for them. They were in the main interview room. I ducked into the observation chamber furtively, ears burning, like someone diving into an adult bookshop. I knew this was going to be the very last thing in the world I wanted to see, but I didn't know how to stay away.

They had made the room as cozy as humanly possible: coats and bags and scarves thrown on chairs, the table strewn with coffee and sugar packets and mobile phones and a carafe of water and a plate of sticky Danishes from the café outside the castle grounds. Damien, bedraggled in the same oversized sweatshirt and combats-they looked like he'd slept in them-hugged himself and stared round, wide-eyed; after the alien chaos of a jail cell, this must have seemed a bright haven to him, safe and warm and almost homey. At certain angles you could see a fuzz of fair, pathetic stubble on his chin. Cassie and Sam were chattering, perching on the table and bitching about the weather and offering Damien milk. I heard footsteps in the corridor and tensed-if it was O'Kelly he would kick me out, back to the phone tips, this no longer had anything to do with me-but they went past without breaking stride. I leaned my forehead against the one-way glass and closed my eyes.

They took him through safe little details first. Cassie's voice, Sam's, weaving together dexterously, soothing as lullabies: How did you get out of the house without waking up your mam? Yeah? I used to do that, too, when I was a teenager… Had you done it before? God, this coffee's horrible, do you want a Coke or something instead? They were good together, Cassie and Sam; they were good. Damien was relaxing. Once he even laughed, a pathetic little breath.

"You're a member of Move the Motorway, right?" Cassie said eventually, just as easily as before; nobody but me would have recognized the tiny lift in her voice that meant she was getting down to business. I opened my eyes and straightened up. "When did you get involved with them?"

"This spring," Damien said readily, "like March or something. There was a thing on the department notice-board in college, about a protest. I knew I was going to be working at Knocknaree for the summer, so I felt sort of…I don't know, connected to it? So I went."

"Would that be the protest on the twentieth of March?" Sam asked, flipping through papers and rubbing the back of his head. He was doing solid country cop, friendly and not too quick.

"Yeah, I think so. It was outside the government buildings, if that helps." Damien seemed almost eerily at ease by this point, leaning forward across the table and playing with his coffee cup, chatty and eager as if this were a job interview. I'd seen this before, especially with first-time criminals: they're not used to thinking of us as the enemy, and once the shock of being caught has worn off they turn light-headed and helpful with the sheer relief of the long tension breaking.

"And that's when you joined the campaign?"

"Yeah. It's a really important site, Knocknaree, it's been inhabited ever since-"

"Mark told us," Cassie said, grinning. "As you can imagine. Was that when you met Rosalind Devlin, or did you know her before?"

A small, confused pause. "What?" Damien said.

"She was on the sign-up table that day. Was that the first time you'd met her?"

Another pause. "I don't know who you mean," Damien said finally.

"Come on, Damien," Cassie said, leaning forward to try to catch his eye; he was staring into his coffee cup. "You've been doing great all the way; don't flake out on me now, OK?"

"There are calls and texts to Rosalind all over your mobile-phone records," Sam said, pulling out the sheaf of highlighted pages and putting them in front of Damien. He gazed at them blankly.

"Why wouldn't you want us knowing you guys were friends?" Cassie asked. "There's no harm in that."

"I don't want her dragged into this," Damien said. His shoulders were starting to tense up.

"We're not trying to drag anyone into anything," Cassie said gently. "We just want to figure out what happened."

"I already told you."

"I know, I know. Bear with us, OK? We just have to clear up the details. Is that when you first met Rosalind, at that protest?"

Damien reached out and touched the mobile records with one finger. "Yeah," he said. "When I signed up. We got talking."

"You got on well, so you stayed in touch?"

"Yeah. I guess."

They backed off then. When did you start work at Knocknaree? Why'd you pick that dig? Yeah, it sounded fascinating to me, too… Gradually Damien relaxed again. It was still raining, thick curtains of water sliding down the windows. Cassie went for more coffee, came back with a look of guilty mischief and a packet of custard creams swiped from the canteen. There was no hurry, now that Damien had confessed. The only thing he could do was demand a lawyer, and a lawyer would advise him to tell them exactly what they were trying to find out; an accomplice meant shared blame, confusion, all a defense attorney's favorite things. Cassie and Sam had all day, all week, as long as it took.