The Thin Blue Line was set in the police station of the fictional English town of Gasforth near London, although Constable Goody wears a North Yorkshire Police helmet plate. One of the main themes was the rivalry between the uniformed squad led by Inspector Fowler (a sort of protagonist figure) and the CID led by Detective Inspector Grim (often Fowler's antagonist, though they were on the same side of the law). Episodes frequently saw the uniformed branch and CID locking horns over similar, or even the same, issues while having conflicting views or methods of operation. Generally the uniformed section triumphed over the detectives, although not without their own foibles. DI Grim provided much of the humour through his misuse of the English language.