‘To me it seems likely that whoever was speaking to them knew them well enough to be able to build a rapport quite quickly,’ Singh told her. ‘The male version of Joe offered friendship to Kian and Bradley, and the same to Cassie but this time as a girl. Whereas to Courtney the female Jo offered competition, and egged her on to become the bully that all popular students have the potential to become. Popularity is power in a school environment, and they must have known just how to push Courtney’s buttons. They worked their way round the students until they found one who responded in the way they wanted. Kian backed off when the talk became intimate, Bradley was never going to open up completely to a stranger. Courtney got bored of it eventually, and Cassie just wanted a friend, nothing more. Leon was the one who responded to Joe enough to be led into a relationship.’

‘That’s pretty scary,’ I said. ‘But surely it was Steve, wasn’t it?’ I was confused; I thought it had been obvious, but Singh didn’t seem completely convinced.

A frown etched lines on his forehead. ‘I still think there’s something we’re missing. It’s highly unusual for a paedophile to target both boys and girls, so this doesn’t quite add up.’

They got the phones only a couple of weeks after Steve started working here, Sasha pointed out. That would explain why he gave phones to all of them – he didn’t know the students well enough yet to know who best to target.

‘So, it’s possible he delivered the phones, got to know the students over time and then gradually worked out which student would be the most receptive to his advances,’ I suggested.

Singh looked thoughtful for a moment, a frown running deep furrows across his forehead. ‘Something doesn’t add up. We’re missing something,’ he repeated. He shook his head. ‘I can’t put my finger on it. I need to see Saul anyway, so I’ll see if he can help with the students’ phones. It’ll be quicker than taking them back to the station and putting them in a queue for the IT techs. Paige, I don’t think I’ll need you again today, so you can go home if you like.’

Sasha and I walked out to the car park together while Singh went to look for the IT teacher. The sky was darker than before, the snow coming down heavier, and I was relieved that I could go home before the roads got too bad.

It looks like you were right about something going on, I told her.

She gave me a rueful smile. I know, but I wish I’d been wrong. And you were the one who spotted the second phones. I’m really sorry about yesterday. I should have believed you.