On her first day back after the Easter break Manchester-based Private Investigator Sal Kilkenny takes on two new cases. The first is to discover who is sending offensive poison pen letters to hotel receptionist Lucy Barker. The second is surveillance work for a couple who want reassuring that there are no nuisance neighbours or criminal activity in the area they're planning to buy a new home. As Sal prepares to stake out the streets a bitter cold snap plunges the country into arctic conditions. Her stress levels are not helped by the escalation of the campaign against Lucy Barker and her inability to nail the perpetrator who maddeningly avoids capture. Plus there's trouble at home as Sal's daughter Maddie seems unable to settle at school. When Sal's normally mundane surveillance duties bring her face to face with a grim discovery and violent crime she's sure that it just can't get any worse before it gets better. Unfortunately for Sal there is more than one surprise in store for her and a nightmarish sequence of events may well turn out to be a matter of life and death...