Could Billy have pinned up that little white book on the board and then sent someone in that he’d lined up to befriend me artificially? This, I decided, was the single most ludicrous suspicion I’d ever had.

Still, I tried as hard as I could to persuade Gibbs that Faith Kendell might be in danger, not because I thought it was likely but because I believed there were no other possibilities.

Don’t ever think that, boys and girls. Don’t be as naïve as I was. There are always other possibilities and plenty of them – ones you couldn’t come up with in your most demented dreams. Or at least I couldn’t, and neither could Chris Gibbs.

Detective Constable Simon Waterhouse on the other hand – he was a different story.

Typed copy of handwritten letter received by Sondra Halliday on 4 January 2015

2 January 2015

Dear Mrs Halliday

I hope you don’t mind me addressing you as such. Your Wikipedia entry tells me you’re married to the chef Oliver Halliday, so it seems the obvious thing to call you.

I hope you enjoy the enclosed novel, Beloved by Toni Morrison. It is a work of genius in my opinion. You might wonder why I, a complete stranger, am sending you a book. It’s because I want to teach you. I don’t know if you’re capable of learning, but I have to try.

(“Why?” I imagine you asking.)

I have to teach you because the only other thing I want to do to you is kill you. Nearly every day, you are doing severe harm to the thing that matters to me most in the world. You have your cause and I have mine; they are not the same thing. They are, rather, stratospheres apart – and you’ve been lying about my agenda in order to further your own. I have an itch inside me, telling me that the only thing I can do to stop this is put an end to you. Then this thing I care about won’t be ruined.

At the same time, I would do almost anything to stop myself from killing you because it would be morally wrong. Unjustifiable. It would make me into something I could not bear to be: a person driven by hate and anger and desperation to become a murderer. That, too, would ruin everything for me, in a different way.

There are some dilemmas that one cannot resolve alone, so I sought help. I don’t expect you know what an Ishaya is, do you? Neither did I, but I was lucky enough to find one and she’s changed my life. Lane. She is the wisest, kindest human being I’ve ever known. She is, in every way, a truly good person. Instead of condemning me for wanting to kill you, which would have made me angrier and more bitter than I was when I first sought her help, she told me she admired my passion, my commitment to the things I held dear. She persuaded me that killing you would be quite wrong not by making me feel ashamed, but by telling me it was completely understandable that I might have murderous impulses.