I was so sure that the object he was determined to put in my hand was a note declaring his interest. The disappointment I felt when it wasn’t … Fuck you, Billy Dead Mates, for putting me through that humiliation. Thank God it was one I was able to suffer privately.

Later that night, in this room I’ve returned to with Charlie, I closed my eyes and pretended Liam was the man who’d given me the white book. I had sex with Niall Greeves all night long in my mind, without knowing his name or seeking his permission.

What kind of person does that? What kind of woman ignores both her husband and her lover as if they don’t exist, in order to build a sexual obsession around a stranger she’s seen for no more than a few seconds?

‘Who does Simon think is Billy?’ I ask Charlie. ‘I know he told you something and asked you not to tell me. He knows, doesn’t he?’

‘I’m not … I mean, he’s not sure, so …’ She stumbles over the words.

‘Who?’

‘Faith Kendell. Or rather, the woman who introduced herself to you as Faith Kendell.’

‘Who is she really?’

‘Did she – hospital woman – have funny kind of grooves on her teeth?’

‘I don’t know. I didn’t notice if she did. We were standing side by side, not facing one another.’

‘Simon wants you to look at a photograph, see if it’s of the woman you met. It should be a match, and then we’ll hopefully be able to give you a name. Is that okay?’

‘I’m happy to look at a picture, but I want a provisional name now. I want to know what you and Simon think you know.’

19) If Kim has been helpful to you in your hunt for a serial killer, you may not withhold from her any relevant information. One to add to my terms and conditions.

I should have tried a more subtle approach. I’ve only strengthened Charlie’s resolve to keep it from me. ‘Let’s just see if the woman in the photo is the one you know as Faith Kendell,’ she says. ‘Make sure it’s the right person.’

When she said those words – ‘the right person’ – Charlie was thinking of Isobel Sturridge, though I didn’t know it at the time. She, Simon Waterhouse, Chris Gibbs, the whole lot of them – they’d decided that Isobel, Liam’s sister, was the infamous news-monopolising serial killer known to the world as Billy Dead Mates.

It’s lucky Charlie wouldn’t give me a name; I’d have laughed till I ruptured every internal organ.