A peaceful demonstration about council service cuts goes tragically wrong when the mounted police are called in to disperse the demonstrators. Clark's team is brought in but their activities are hindered by the chief constable heading the investigation.

An assistant chief constable is accused of sexual misconduct, and Det. Sgt. Connell's friend Kate is implicated. Det. Supt. Clark's search for a missing tape brings him back into contact with Angela Berridge.

Det. Supt. Clark investigates the involvement of Special Branch in the 'execution' of police informant Declan Harris, and gets the chance to settle old scores with Det. Chief Supt. John Deakin.