When cold-crime enthusiast Ellen Barker is murdered, a photo of Dan Griffin is found at her house. Griffin is interviewed by the murder team, who realise that Ellen was a friend of his. The senior investigating officer assigned to Ellen’s murder investigation is DCI Grace Mackie, one of Sasha Miller’s contemporaries from their Hendon training. Griffin is convinced that the last case Ellen was looking at could lead to her killer, and heads to Minchampton, where a woman called Sally Tunstall was murdered 25 years ago by local lad Dougie Haynes.