It all began one wintery Sunday night in Joe Allen, the famous theatrical restaurant in the heart of London’s Covent Garden. It was cold and wet outside, but in Joe’s the atmosphere was warm, the lights were dim, the drinks and the conversation were flowing. I sat with a group of friends at our usual corner table. At least some of us meet virtually every weekend. We call ourselves Sunday Club. It’s a casual, comfortable affair. Whoever is free turns up.

This particular Sunday we began to play our version of the truth game, a favourite past-time, particularly if we have new Sunday Clubbers present. Each member of the group asks a question which each in turn must answer – allegedly truthfully! It can be something trivial, requiring you only to recall your best ever holiday or most memorable meal. It can be something far more serious and insightful.

My partner, Amanda Barrie, asked the rest of us to reveal our greatest life changing moment. It’s a good question, and a tricky one.

I found myself imagining what might happen if one of us responded with something which unwittingly unveiled a deadly secret. A secret which only meant anything to one other member of the group. And what if that other person was potentially extremely dangerous? What if an apparently so very ordinary occasion led to a sequence of at first disquieting and later terrifying events, and even to murder?

My crime writer’s imagination began to run riot.

Think about your friends. Think about convivial times spent sitting around a kitchen table, in a pub or a restaurant. You are easy together. You know each other well. You are relaxed in each other’s company.

But think if there were just one person in your immediate circle who might not be what they seem. One person with a terrible past who is capable of extreme violence and depravity.

You begin to doubt them all. First one friend. Then another. Maybe you even doubt yourself.

For a time at least, the habit carries on. You continue to meet in the same old familiar way. The same familiar group of people eating, drinking and chatting together. But ultimately events take a quite cataclysmic turn. And you become sure that one of those you consider to be a good friend must be responsible.

I was instantly fascinated by the idea.

I would try to create a kind of Friends UK meets Ten Little Indians, with a fictionalised Joes – a place where I suspect so many such ideas, primarily probably for plays and TV series and films, have been spawned – as the back-drop. And there would be a fictionalised Sunday Club, too, of course. Everyone in the real life group is, of course, beyond any kind of reproach or suspicion!

Later I stepped out of Joes into Exeter Street, quiet and shadowy on a Sunday night, and imagined my potentially lethal protagonist doing the same thing. He, or she, would want to be alone, I thought, to mull over the night’s events. To consider what do next. To plan an awful convoluted revenge.

I thought my villain might head for the river, which always attracts me when I want to clear my head, and lurk there on the embankment, watching the mighty Thames flow by, plotting, scheming, dreaming up a nightmare…

The title for such a book seemed quite obvious.

Friends to Die For.

What else?