Hemmingway and Harman investigate a break-in at a doctor's surgery, but the situation becomes complicated when they catch youth Billy Aldridge in possession of a quantity of stolen drugs samples. When the surgery receptionist confesses to the crime, Hemmingway suspects that she is trying to take the rap for someone else - but also has suspicions that the GP running the surgery has something to hide. Later, she confronts Aldridge, who claims the doctor paid him to keep quiet about the fact that he is sleeping with an under-age girl. Meanwhile, Perkins helps Keane and Fletcher trap a cowboy builder with a sideline in blackmail, and Fletcher is assaulted on his way home from work.