‘Hey there, Mr Attitude,’ I said. I looked back at Lucas, who was clearly hurt. ‘National Youth Theatre? Congratulations. I hear that’s an incredibly difficult audition to pass.’ Joe gave me a side-eye and a half-smile. ‘So that’s Lucas,’ I said, still pretending I was talking into my phone. ‘I could totally see and hear him. You were pretty harsh.’

I remembered that I was going to try again to talk to Joe’s people, and spun round. ‘Lucas!’ I called. I waved my arms. ‘Hey, Lucas Ingleby? You OK?’

He couldn’t hear me. I turned back to Joe, who whispered, ‘How did he feel to you?’ I could see his anxiety. He was the Joe I knew again now. ‘My mind always comes back to him, and that must mean something. Maybe he …’

I interrupted. ‘You were much worse to him than he was to you. You f-bombed him. He was just mildly taking the piss.’

He looked surprised. ‘D’you think?’

We both jumped as a bell rang. It meant we had to go to registration. I was standing outside a geography room that was a tutor room in my time too, so lots of people were suddenly pushing past.

‘See you later,’ I said, and I reached out so my hand could float through his, and then set off down the corridor, alone, between the crowds of Joe’s people and mine, shivering as I went.

I tried to concentrate all day, but I’d stopped caring. I cared about Joe, who was dead, but no one knew why. Joe, who was going to visit Mum and Sasha again today. I cared about my nephew and my sister, and Zara and Coco, and Izzy. I had no space left for quadratic equations after all that. I was going to get some GCSEs, but, more importantly, I was going to work out what had happened to Joe Simpson and free him from this glitch. I was hoping quite hard that I had it in me to do both those things at once.

Izzy, though, was pissed off all day. She barely spoke to me.

‘Sorry,’ I whispered when we were in tutor.

‘What for?’ she said tightly. ‘You haven’t done anything.’

‘Exactly. What’s up?’

She shook her head. ‘Doesn’t matter. There was something I was going to talk to you about this morning, but you weren’t there. And you always run off after school. Are we even friends any more?’

‘Oh, Izzy!’ I felt terrible. ‘Of course we are! I love you. Let’s do something at the weekend.’ An idea was forming in my mind. ‘In fact, why don’t we go to London, like you said?’

She raised her eyebrows. ‘Really?’

‘Really.’