It's been 25 years since Alfred Chalmers was convicted of the gruesome murder of four young women in Edinburgh. Isobel McArthur, Scotland's first Chief Superintendent, was the woman responsible for putting him behind bars, but the case has haunted her ever since. Now, with her retirement approaching, McArthur decides the time has come for answers. But her decision rips opens old wounds and McArthur is soon caught up in a web of corruption, psychological mind-games and deceit.