Hi Abby! Yes, I can totally do tomorrow actually. I could come over this afternoon if that suits? I have a club so can’t do straight from school – would 5.30 be OK? Or is that too late? Also what’s the address? Thanks! Ariel

I hadn’t expected it to work. But it had, straight away, and this made me feel weird. I hoped Joe would be all right with it. It was one thing to approve my babysitting plan in theory, but here it was, under way, and that was something different. If he felt it was too much I’d cancel tonight’s meeting after I’d seen him.

I knew that if he didn’t turn up one day it might mean he’d managed to change things and not die. If he repeatedly didn’t turn up then I was going to go and look for him in real life, as a thirty-five-year-old. We had agreed that. It was the outcome I most wanted. I felt that, together, Joe and I could do anything. We ought to be able to change the course of history. It was impossible, and we were impossible, and so it should have worked.

I had something I needed to ask him to do before that happened.

Abby replied five minutes later, saying, OMG lifesaver! See you at 5.30! X and giving me the address I already knew. I was smiling so hard at my phone that I almost walked into Ms Duke.

‘Ariel,’ she said, steadying me with a hand on my shoulder. ‘I was hoping to catch you. Have you got a second?’

I felt instinctively guilty and tried to think what I’d done. The answer was: nothing. I’d been doing better since I met Joe because nothing puts one’s own problems into perspective like meeting a boy who has been stuck between life and death for twenty years. Also, I was never in trouble with Ms D, and she looked out for me. It was her job to check that I was all right.

‘Yes,’ I said. ‘Sure.’

She smiled. ‘Don’t worry. Nothing bad. We just haven’t caught up for a while, have we? A few of your teachers have said that you seem to be in a better place lately. I know you’re good at masking, so I wanted to see how things really are.’

She walked companionably beside me, and I worked hard to pretend there wasn’t a girl with a high ponytail and platform trainers walking on the other side of her. I pulled my hair back and tied it into a ponytail too, with the elastic I had on my wrist, because I liked the way the ghost girl’s hair swung around. I looked at her out of the corner of my eye and walked in step with her, swinging my hair in time with hers.