That easy. On the corridors above us and below, the older girls and the younger ones had gone back into their common rooms and closed the doors. There was no sound anywhere, none at all. That white silence came sifting down again, piling into little drifts in the corners, slipping down our backs to collect in the folds of our clothes.

Holly was a cop’s kid. Holly was my star witness. Holly was the one who had brought me that card. Even after I’d seen her here, deep in her own world, I had somehow thought she was on my side.

‘OK,’ I said. Easy and loose, like it was nothing, nothing at all. Felt Conway’s eyes, on me, not on Alison. ‘What’d you see?’

‘After the assembly. The one where they told us about Chris. I was . . .’

Alison was getting that look again, the one from earlier: slack and dazed, like someone after a seizure. ‘Stick with me,’ I said, smiling away. ‘You’re doing great. What happened after the assembly?’

‘We were coming out of the hall, into the foyer. I was right beside Holly. She looked round, just quickly, like she was checking if anyone was watching her. So I noticed that, you know?’

Observant, just like I’d told her that morning. Prey animal’s fast eyes.

‘And then she stuck her hand down her skirt, like in the waist of her tights?’ A snigger, limp and automatic. ‘And she pulled out this thing. Wrapped in a tissue.’

Making sure she wouldn’t leave prints. Just like Mystery Girl had done with the hoe. I nodded along, all interested. ‘That’d catch your eye, all right.’

‘It was just weird, you know? Like, what would you keep down your tights? I mean, ew? And then I kept looking because some of it was sticking out of the tissue, and I thought it was my phone. It was the same as mine. But I checked my pocket, and my phone was there.’

‘What did Holly do next?’

Alison said, ‘The lost-and-found bin’s in the foyer, right at the door of reception. It’s this big black bin with a hole at the top, so you can put things in but you can’t get them out? You have to go to Miss O’Dowd or Miss Arnold and they have the key. We were going past reception, and Holly kind of ran her hand across the bin – like she was just doing it for no reason, she didn’t even look at it, but then the phone wasn’t in her hand any more. Just the tissue.’

I saw Conway’s eyes close for a second on the Should’ve searched. She said, from her corner, ‘How come you didn’t say this to me last year?’

Alison flinched. ‘I didn’t know it had anything to do with Chris! I never thought—’