Nick investigates when the unpopular special constable Hector Cowley disappears, shortly after having a dispute with Betty Such and her son Simon. Nick and the team fear for Hector's life when Simon is spotted wearing his items and the officers are certain the Such duo have disposed of the officer, but the truth may be far more complicated. Meanwhile, Greengrass receives a visit from old flame Ellen Birley and allows her to stay with him, a decision he comes to regret when she takes over his life and invites her husband to live with them.