‘I never said I was crying. I wasn’t. I’m saying I might have been giving someone else a tissue, I don’t remember. But I do know the phone was on the floor.’

I said, ‘I think you took Selena’s phone out from behind her bed and found a good way to ditch it. The lost-and-found bin, that was smart. It worked well. It almost worked for good.’

Holly’s mouth opened, but I held up my hand. ‘Hang on a sec. Let me finish first, before you tell me if I’m right or wrong. You knew there was a chance we’d search the school. You knew if we found the phone, we’d be talking to Selena. You knew what police questioning is like; let’s face it, there’s better ways to spend your day. You didn’t want Selena put through that, not when she was already traumatised about Chris’s death. So you binned the phone. Does that sound about right?’

It was an out: an innocent reason why she would have wanted the phone gone. Never take the out. It looks safe as houses. It takes you a step closer to where we want you.

Mackey said, without glancing up from his new toy, ‘You don’t have to answer that.’

I said, ‘No reason why you shouldn’t. You think we’re going to press charges against a minor for concealing something that might not even be evidence? We’ve got a lot more on our minds. Your da can tell you himself, Holly: if you’re after something big, you’re happy to let the small stuff slide. This is small stuff. But we need to clear it up.’

Holly watched me, not her dad. Thought, or I thought she did, about that moment when she had seen me understand.

She said, ‘Selena didn’t kill Chris. No way. I never worried that she did, not even for a second. She doesn’t work like that.’ Straight-backed, straight-eyed, trying to shove it into my head. ‘I know you’re thinking Yeah, right. But I’m not just being naïve. I know with most people you don’t have a clue what they’re capable of. I know that.’

Mackey’s piece of clay had gone still. It was true: Holly did know that.

‘But with Selena I do. She wouldn’t have hurt Chris. Ever. I swear to God, it’s totally impossible.’

I said, ‘Probably you’d have sworn to God that she wouldn’t go out with Chris, either.’