‘Is it possible that Cassie is telling the truth about having a key?’

I suppose it’s possible, although I don’t know what she could have done with it between opening the door and her being caught. And where would she have got it from in the first place? Liz asked. I’ve been keeping Steve’s office locked, at least until the governors make a decision about who is going to take over the headship. There are only two keys that I know of – I’ve got one, and the other is in Karen’s office. She’s our school business manager.

‘Surely Steve must have had one?’ Singh asked.

Well, of course he did, but his personal effects are with the police. He will have had his keys with him on the day he died, I assume.

Could Cassie have stolen Steve’s key while they were on the trip? Leaving the mystery of Cassie’s key unsolved, we set off home.

‘What are those kids hiding?’ Singh mused. ‘Did you see the way Cassie looked at Bradley?’

‘Yeah, I don’t know what that was about. He changed his tune pretty quickly. It must be something to do with her phone being missing, but I don’t know what.’

‘Whatever it was, Courtney is obviously in on it too. They all know something and they’re keeping it secret.’ He scratched his chin, his stubble making a rasping noise as he did. ‘Do you think they could be involved in Steve’s murder?’

‘I have no idea,’ I replied, stifling a yawn. ‘I can’t quite see them all banding together to kill Steve, if that’s what you’re wondering. You’d think Mike and Sasha would have noticed the whole group trooping off into the woods on Saturday morning.’

‘You’re not very helpful when you’re tired, are you?’

‘I’m solar powered,’ I replied.

Before Singh dropped me off I turned to him.

‘Was Liz right? Did Steve have keys on him when he died?’

‘That’s what I’m going to check, first thing in the morning. Until then, though, I think we can both manage a couple of hours’ sleep.’

‘I doubt it,’ I replied. ‘Everything is going to be going round in my head, I don’t think I’ll get much rest now.’