As punishment for messing up a kidnap rescue and shooting a dog in the process Detective Superintendent Sandra Pullman (Amanda Redman) is assigned to the newly created unsolved murder squad. Due to a manpower shortage her team is made up of veteran detectives seconded back into the police force who bring a 1970's attitude to modern policing rather than vice versa. The team's first case is to re-investigate a twenty year old murder conviction which has suddenly become unsafe due to police corruption. Sifting through the lies, dubious motives and the police cover up during the first investigation, the unorthodox methods of the dinosaur detectives eventually discover what really happened twenty years ago, clearing up two murders and an armed robbery in the process!