The cathedral town of Lafferton seems idyllic, but in many ways it is just like any other place. As part of the same rapidly changing world, it shares the same hopes and fears, and the same kinds of crime, as any number of towns up and down the land. When one day DC Simon Serrailler is called in by Lafferton's new Chief Constable, Kieron Bright, he is met by four plainclothes officers. He is asked to take the lead role in a complex, potentially dangerous undercover operation and must leave town immediately, without telling anyone - not even his girlfriend Rachel, who has only just moved in with him. Meanwhile, Simon's sister Cat is facing difficult choices at work that will test her dedication to the NHS. But an urgent call about her and Simon's father, Richard, soon presents her with a far greater challenge much closer to home. To complete his special op, Simon must inhabit the mind of the worst kind of criminal. As the op unfolds, Lafferton is dragged into the sort of case every town dreads. And Simon faces the fight of his life.