The tips of my fingers were prickling with how much I wanted to get in there. “We’ll let him wonder for another fifteen minutes,” I said. “Then you go in.”

“Just me?”

“He’ll see you as less of a threat than me. Nearer his age.” And there was the class gap, too: a nice middle-class boy could easily discount an inner-city kid like Richie as some idiot skanger. The lads would have been gobsmacked if they had seen me letting a brand-new newbie loose on this interrogation, but Richie wasn’t quite your ordinary rookie, and this felt like a two-man job. “Just settle him, Richie. That’s all. Find out his name, if you can. Get him a cup of tea. Don’t go anywhere near the case, and for the love of all that’s holy don’t let him ask for a lawyer. I’ll give you a few minutes with him, and then I’ll come in. OK?”

Richie nodded. He said, “You think we’ll get a confession out of him?”

Most of them never confess. You can show them their prints all over the weapon, the victim’s blood all over their clothes and CCTV footage of them whacking her over the head, and they’ll still be spewing out injured innocence and howling about frame-ups. In nine people out of ten, self-preservation goes deeper than sense, deeper than thought. You pray to get the tenth person, the one built with a crack in the self-preservation where something else runs deeper still—the need to be understood, the need to please you, sometimes even conscience. You pray for the one who, somewhere darker than the inside of bone, doesn’t want to save himself; for the one who stands at the top of the cliff and has to fight the urge to leap. Then you find that crack, and you press.

I said, “That’s what we’re aiming for. The Super comes in at nine; that gives us six hours. Let’s have this ready to hand over to him, all wrapped up and tied with a bow.”

Richie nodded again. He pulled off his jacket and three heavy jumpers and dropped them on a chair, leaving him narrow and gangly as a teenager in a long-sleeved navy T-shirt that had been washed thin. He stood at the glass, no fidgeting, and watched the guy hunch lower over the table until I checked my watch and said, “Go.” Then he ran a hand through his hair so it stood up on end, got two cups of water from the cooler, and went.

He did it nicely. He went in holding out a cup and saying, “Sorry, man, I meant to bring this in to you before, only I got caught up … Is that all right for you? Would you have a cup of tea instead, yeah?” His accent had got thicker. The class thing had occurred to him, too.

Our man had jumped half out of his skin when the door opened, and he was still catching his breath. He shook his head.