An intruder is shot dead at a Territorial Army base. Clark is forced to accept help from Angela Berridge, an official from the Home Office, and finds that the activities of MI5 and Special Branch undermine his 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.