I think I know a lot more than you realise. You blamed Steve for your brother’s death, didn’t you? I could see that this had hit home by the change in expression on her face, so I pushed on. You wanted to make him pay, by ruining his reputation. You set up Bradley and Courtney, and engineered a safeguarding scandal to get Jane out of the way, then made sure Steve got the job in her place.

That was easy, she replied with a harsh laugh. I was on the interview panel, and I knew I could ask questions that made him look like the best candidate. The arrogant bastard thought he’d walked it because of his own skills, but I had never intended for the governors to choose anyone else.

Once he was in the post, you started messaging the students, looking for one to groom, and saved the messages to Steve’s school account. You had a problem, though, didn’t you? I looked at Cassie, and Liz followed my gaze.

She saw me, with the video cameras, Liz told me, her face twisted with spite. I didn’t know if she’d realised exactly what she’d seen. She’s not very bright. But I knew I needed to keep her on my side. She’s been useful, though.

I shook my head in disbelief. Did you think she’d keep your secrets forever? Even after you killed Steve?

I didn’t always intend to kill him, she said nonchalantly. I was just going to get him arrested for grooming, at first. But then he was here, in this school, my school, trying to change it, behaving like the arrogant bastard he has always been, and I couldn’t stand it. Liz’s eyes burned with fury and I felt my heart rate increase with fear at what she might do next.

And you thought you could frame Leon for his murder?

Or Cassie, she replied with a callous shrug. Either would do. Leon made it easier for me, though. He stumbled on Steve’s body and picked up the knife. He cut himself. If he hadn’t seen me it would have been easier. She shook her head, as if she were just talking about a minor inconvenience in her life, not a serious crime.

While I had been trying to keep her distracted, I was planning. Could I grab Cassie and make it out of the room before Liz reached us? The room was small, and Cassie’s chair was blocking Liz’s path out of the room. Putting my hands on Cassie’s shoulders, I applied enough pressure to slide the chair backwards slightly and wedge it in the gap. Noticing what I was doing, Liz lunged forwards, but I slipped my hands under Cassie’s arms and hauled her towards the door, flinging it open and dragging the girl into the corridor.