That’s stupid, Bradley responded.

Cassie turned as she replied to him. Don’t call me stupid. I’m the least stupid person here.

Yeah, whatever.

The older girl shook her head and turned back to Courtney and Kian.

Mr Wilkinson didn’t …

Yes he did, Kian replied. We all know he did. We need to tell someone.

No, Courtney replied. That’s a bad idea. We’ll all be in trouble.

I was wrenched away from observing the rest of the conversation by the arrival of the deputy head. She looked past me, out of the window, and frowned when she saw the four students standing together.

Sasha, go and chase those four back to class, please. I don’t know what they’re doing there but it’s probably nothing useful.

Sasha looked like she was about to protest, but then glanced out of the window to see who Liz was talking about. When she realised which four students it was she sighed then headed down the stairs, and Liz went into Leon’s room to see DS Singh. I followed.

What on earth happened in here? she asked, her eyes roving over the disarray. Did someone break in?

‘That’s what we want to ask you,’ Singh replied. ‘We need to check the CCTV from outside the building. There are no obvious signs of a break-in, so we assume it was someone with authorised access to the building. Does the school keep a log of who has entered the building and when?’

No, we can probably see when someone used a fob, but they’re not individually identifiable. The deputy head wore a concerned frown. How do we know if anything has been taken?

‘I don’t think we can, without asking Leon himself.’

Could it have been Leon? Miss Marcek asked. Could he have crept back in here to get something from his room?

‘I doubt he would have left it in such a mess,’ Singh replied. ‘Even if he didn’t know where he’d left whatever he was looking for, he probably wouldn’t have wanted to leave any trace of himself. No, I think this is most likely someone else.’ He looked around him, hands on his hips. ‘Can we find out if any students were out of class today?’

I’m sure I would have been informed of any truancy, but I’ll check, Liz replied.

I thought about Cassie and Mike talking earlier and wondered if it was connected. Could one of them be responsible for this? I remembered the look on Mike’s face when I had interfered and decided I wouldn’t mention it just yet; I didn’t want to wind him up unnecessarily. I didn’t trust him not to retaliate.