Detective Chief Inspector Harry Nelson is sitting by a pool with a glass of beer in his hand, thinking dark thoughts. It is evening and fairy lights, strung in the trees, are twinkling manically in the still water. Nelson’s wife Michelle is sitting beside him, but she is carrying on an intense discussion about highlights with the woman at the next table and has her back turned. Michelle is a hairdresser so this is her area of expertise, and Nelson knows better than to expect a pause in the monologue. His own area of expertise – murder – is less likely to prove a promising starting point for conversation.

When Nelson informed Michelle that he had a week’s holiday still owing, she suggested that they go somewhere ‘just the two of us’. At the time, he had quite liked the sound of this. Their eldest daughter, Laura, had left for university in September and their seventeen-year-old, Rebecca, was unlikely to want to spend an entire week with her parents. ‘Besides,’ said Michelle, ‘she won’t want to miss school.’

Nelson had grunted sceptically. Rebecca hardly ever seemed to go to school, her life as a sixth-former apparently consisting entirely of mysterious ‘free periods’ and even more mysterious ‘field trips’. Even her A-Level subjects are incomprehensible to Nelson. Psychology, Media Studies and Environmental Science. Psychology? He’s seen enough of that at work. Every so often his boss, Gerry Whitcliffe, will wheel out some weedy psychologist to give him an ‘offender profile’.