I said, ‘Why, but? Say she had Chris’s phone, or access to it: why not dump it in the lost-and-found bin along with Selena’s, if she was trying to take suspicion off her lot? Or if she was trying to frame Selena, why not leave both phones behind her bed? There’s no reason why she’d want to do different things with the two phones. Holly’s out.’ A couple of hours too late. We had Mackey for an enemy now, not an ally.

Conway thought that through for two fast steps, gave it the nod. ‘Rebecca. All on her ownio.’

I thought of that triple creature, still and watching. All on her ownio seemed like the wrong words.

Conway said, ‘We still don’t have enough on her. It’s all circumstantial, and the prosecutors don’t like that. Specially when it’s a kid. Extra-specially when it’s a little rich kid.’

‘It’s circumstantial, but there’s a load of it. Rebecca had plenty of reasons to be pissed off with Chris. She was able to get out at night. She was seen with the weapon the day before the murder. She’s one of the only two people who could’ve put Chris’s phone where it was found—’

‘If you believe a dozen stories from half a dozen other teenage girls who’ve all lied their little arses off to us. A decent defence barrister’ll have reasonable doubt all over it inside five minutes. Plenty of girls had better reasons to be pissed off with Chris. Seven others could get out at night, and that’s just the ones we know about; how do we prove no one else had found out where Joanne kept her key? Chris’s phone: Rebecca or Selena could’ve found it wherever the killer dumped it, stashed it behind the bed while they worked out what to do with it.’

‘So what was Rebecca doing messing about with the murder weapon?’

‘Gemma made that up. Or Rebecca was there to buy drugs. Or she actually was into gardening. Pick your favourite.’ Conway’s stride was lengthening. By now I knew that was frustration. ‘Or she was scouting for Julia, or Selena, or Holly. We know they’re out, but we’ve got nothing solid to prove it. Which means we’ve got nothing solid that proves Rebecca.’

I said, ‘We need a confession.’

‘Yeah, that’d be great. You go pick us up one of those. Get next week’s Lotto numbers, while you’re at it.’

I ignored that. ‘Here’s what I’ve spotted about Rebecca: she’s not scared. And she should be. Her situation, anyone but an idiot would be petrified, and she’s no idiot. But she’s still not scared of us.’

‘So?’

‘So she must think she’s safe.’

Conway shoved a branch out of her face. ‘She fucking is, unless we come up with something amazing.’