Holly whipped round on Conway. ‘Are you stupid ? I didn’t kill Chris. We can stay here all night and you can come up with four million different reasons I could’ve killed him, and I still won’t have done it. Do you actually think I’m going to get confused enough that in the end I’ll just be like, “OhmyGod, you know what, maybe I totally did climb up a tree and drop a piano on his head because I hated his poncy haircut”?’

Mackey was grinning. ‘Nicely put,’ he told her.

Holly and Conway didn’t even hear him, too focused on each other. ‘If you didn’t,’ Conway said, ‘then you know who did. Why did you hide that phone?’

‘I told you. I didn’t want Selena—’

‘You said she hadn’t been in touch with Chris for weeks before he died. The phone would’ve showed that. What’s incriminating there?’

‘I didn’t say it was incriminating, I said you’d have given her hassle. Which you would have.’

‘You’re a cop’s kid, you know better than to conceal evidence in a murder case, but you do it to save your mate a bit of hassle? Nah. No way.’ Holly tried to say something, but Conway’s voice came down hard on top of hers. ‘One of you four had been texting Chris from that phone, after he split up with Selena. Arranging meetings with him. One of you four had arranged to meet him the night he died. Now that’s incriminating, amn’t I right? That’s something you’d want to cover up.’

‘Whoa whoa whoa,’ Mackey said, lifting a hand. ‘Hang on a minute there. That’s your evidence? Texts sent from someone else’s phone?’

Conway said, to Holly, ‘A hidden phone, that you had access to. You and no one else that we know of, except Selena, and we’re satisfied Selena didn’t send the texts.’

Mackey said, ‘A phone kept in a room that four girls share. Are the texts signed in Holly’s handwriting, yeah? Got her prints on them?’

I copped, finally, why Mackey had told me that touching little tale about how Holly wound up boarding. He had been telling me how much she loved her friends. Anything we got out of her, there was how he was going to shoot it down: Holly’s protecting her friends. Prove she’s not.

Hard to be sure of anything, ever, with Mackey. I was sure of this: he would throw an innocent sixteen-year-old under a bus without thinking twice, if it would save his kid.

A hundred per cent positive of this: he’d throw me and Conway.