The Wimbledon Poisoner by Nigel Williams
Henry Farr is forty years old. He is suburban, average, conventional - and desperate to be rid of his wife, Elinor. Inspired by a grisly episode in Wimbledon's local history, Farr begins to concoct a recipe for the perfect murder. But his plans go terribly, terribly wrong - and before long, poor Henry's best efforts to set himself free, in fact send him spiralling wildly out of control.