A family feud has explosive consequences that the officers from Sun Hill have to clean up… The blue touch paper is lit when a letter bomb is sent to Alan Cooper, the manager of his own company. His terrified assistant, Dani Foster, is holding the package when Sergeant Callum Stone and Pc Ben Gayle arrive on the scene. They empty the offices but Ben fails to calm the increasingly hysterical Dani, who throws the package on the floor. It explodes, covering the young woman in a white powder that turns out to be harmless. But someone clearly has it in for Alan.

DC Grace Dasari questions Alan and his pregnant wife, Lisa, but Alan is sure the whole episode was nothing more than a stupid stunt by an idiot. Grace is not convinced and she and Callum dig deeper… What they uncover takes them both by surprise. Alan’s enemy is his brother, David, and he definitely means to harm Alan. They had worked together until recently, when Alan sacked David. Searching David’s home, the officers discover bomb-making gear.

Callum and Grace find a distressed David sitting in a park. Grace talks to him and finds out that David’s upset with Alan for gambling his wife and family for an affair with Dani. The officers think the danger’s over but then David admits he has sent another package to Alan’s family home…