This is a detective novel without a police officer. I am in huge awe of anyone who can write a taut police procedural novel, but the stories that have always stayed with me longer after the book has been closed show the other side of that tapestry. I’m fascinated by what happened before the police arrive, and what is left behind after they have gone. The moment in classic crime fiction where the detective surmises the killer’s motive and methodology always seem to me like synopses for fabulous novels that would never be written. The ‘innocent’ who kills, the ordinary person who is caught up in extraordinary and terrible events.
And this is not a whodunit, but a whowasitdunto? I was intrigued by the challenge of introducing my murderer within the first few pages – from the moment we meet Rex, we know that he has killed two people – but not revealing the victims until much later in the book. Even I wasn’t sure who he was going to murder for a long time – and his victims changed twice during the writing process.
I wanted to write about students because it’s such an intense, irresponsible time of life – all that time, none of that wisdom – that it’s astonishing more of us don’t come down from university with a diploma in one hand and a pair of handcuffs on the other. Finding the right setting was crucial: for a while, I had them all living in West End squat that was inspired by my old flatshare in Wimpole Street. It didn’t work; too urban, too connected to the outside world. They needed to live in complete isolation to descend into the folie a trois I had in mind. From the moment I moved them all into that dank, crumbling house in Highgate, I knew they would behave as badly as I needed them to.
The novel is also set when, and where, it is for more prosaic (and lazy) reasons. Without time or money to spend on research, and a biological deadline in the form of my first pregnancy, I had to write about something I knew. I was living on the edge of Queen’s Wood when I began the book, I was spending a lot of time on the Suffolk coast where the present-day action is set, and like Karen, the narrator, I had been a student in 1997. In those respects alone is The Poison Tree an autobiographical novel. I would like to stress that none of my friends were murdered in the writing of it.
The Poison Tree is published by Hodder & Stoughton