On the night of a wedding celebration, one guest meets a grisly end when he’s killed in a hit-and-run. A card bearing the number ‘5’ has been placed on the victim’s chest. DI Clare Mackay, who recently moved from Glasgow to join the St Andrews force, leads the investigation. The following night another victim is struck down and a number ‘4’ card is at the scene. Clare and her team realise they’re against the clock to find a killer stalking the streets of the picturesque Scottish town and bent on carrying out three more murders.

To prevent further deaths, the police have to uncover the link between the victims. But those involved have a lot more at stake than first meets the eye. If Clare wants to solve the case she must face her own past and discover the deepest secrets of the victims – and the killer.