‘I’m not hurt.’

She looks me up and down as though she can’t quite believe what she’s seeing. ‘You drove all the way across Bristol and you can’t remember it? Fuck, Claire! That’s really scary.’

‘I know.’

‘You can’t remember anything at all?’

‘Nothing.’

‘Right.’ She gives me a long look. I can tell she’s freaked out, even though she’s trying hard not to show it. ‘I think I need to get you to a doctor. Are you okay to drive? Silly question. I’ll drive the car. Caleb can pick mine up later.’

As we head back to Knowle I tell her everything I can remember, about the photo album, about finding myself parked in a street I didn’t recognize, about the guy on the bike, speeding off, running out of petrol and checking my phone. I don’t tell her about seeing Billy’s dead body on the bonnet of my car.

‘And then I rang you,’ I say.

‘Fucking hell, Claire.’ She presses her foot to the accelerator as the traffic light turns green. ‘I don’t know what to say. When you WhatsApped me that first photo I thought maybe you’d taken it by accident or pressed the wrong button or something but then you sent a few more and I thought you were having a laugh but I didn’t get the joke.’

She gives me a sideways look. ‘Who’s the blonde in the photo with Mark?’

‘Edie Christian, Billy’s form tutor.’

‘Why did you take a photo of them? Is he having an affair or something?’

‘I don’t know. I can’t remember anything. Oh my God.’ I cover my mouth with my hands as the cars in front slow to a near halt and a cyclist overtakes us. ‘What if the cyclist has reported me to the police for kicking him? The woman who stopped her car had a phone in her hand. She probably took a photo of my numberplate. The press will have a field day if they find out what I did.’

‘It’s okay.’ Liz taps me on the leg, then puts her hand back on the steering wheel. ‘You’re ill. You didn’t know what you were doing. Is that the photo album you were on about?’ She glances at the two books on my lap. ‘Can I see it?’

‘Of course.’ I open a page and hold it up so she can see. The traffic in front of us is still at a standstill.

‘Jesus Christ, Claire. Who did that?’

‘Billy, I think. The writing looks like his and it’s the same sort of thick black marker he uses.’

‘But why?’

‘I don’t know.’

‘I thought the police searched the house?’