Det. Chief Supt. Henderson returns to work following the death of his wife in a car crash. An operation is started to end an outbreak of piracy in the Mersey. An organised gang overwhelm a would be rescuer to steal their boat.
Det. Supt. Frank Mathews puts together an operation in the attempt catch whoever is throwing body parts in the Mersey. Irishman Gerry Darcey's arrest causes a stir when he demands to speak to the Assistant Chief Constable.
The drugs squad go partying undercover for a raid on an "acid ship" party, but things don't go according to plan; PC Ronnie Barker is finding the pressure too great after infiltrating a gang of right-wing extremists.
