Apparently no one can decide if I’m a danger or in danger.

‘Your worry’s understandable,’ says Waterhouse. ‘I’m hoping that once you’ve had your session with our sketch artist and we’ve spread the image of the man who gave you the book far and wide, we’ll be well on our way to catching Billy. In the meantime, I’m glad you’re going away with Charlie tomorrow. That’ll give you some protection while we make progress.’

My tour-in-reverse, in search of the mysterious gig venue that I can’t identify. I’m dreading it.

‘Let me ask you something. Who might want to harm you?’

‘Apart from members of the public who tweet me death threats because I’m not funny?’

‘Are there many of them?’

‘No, and please don’t waste your time tracking them down. They’re saddos letting off steam. I feel sorry for them. Who might want to harm me seriously? Gabe, Liam, Drew. I can’t think of anyone else.’

‘Your husband, your ex-boyfriend and your brother.’ Waterhouse makes a note. I imagine it says something like ‘Only knows three people in entire world. All probably want her dead.’

‘To turn that question around and look at it another way: who, if they’d planned to kill six people and you were one of the six, might not be able to bring themselves to harm you, even if, theoretically, they wanted to?’

This one I have to think about. I’m surprised by my conclusion. ‘Strange as it sounds … the same three people. Gabe. Liam. My brother Drew,’ I say. ‘No one else would care enough to spare me.’

I was surprised when I met Charlie and she was a woman. Waterhouse hadn’t mentioned it.

My first thought: if a Charlie can be a woman, maybe a Billy can too.

When she introduced herself to me – the police officer who was to be my chauffeur for however long it took – I knew it was too late to call off the gigless tour. I considered feigning an illness: sharp pain in my stomach. Maybe that ringpull I swallowed could be brought into play, I thought.

I didn’t want to let anyone down, but I feared I would, whatever I did. If I helped them find the man who gave me the little white book, I’d be leading them to the wrong person. I didn’t know why I was so certain that man wasn’t Billy, but suddenly I was.

So why had I felt so uncomfortable when he approached me? My instincts had told me there was danger …

Not danger of murder, though.

I shook my head to banish the incoherent swirl of thoughts. It would be easier, I knew, if I stopped thinking, got into the car and let Sergeant Charlie Zailer drive me around the country as planned. It wasn’t as if there was anything else I wanted or needed to do at that moment.

She was tall and thin, with wavy dark brown hair cut to just above shoulder-length, pale skin and no make-up apart from bright red lipstick. ‘You’re not wearing uniform,’ I said.