Bulman, Willis and Doran are working undercover at the docks trying to identify the ringleaders in a series of bicycle thefts. Back at the office Detective Inspector Rainbow is not happy with their methods. After an accident on the quay Bulman starts to get romantic ideas about the lady doctor.
When counterfeit Deutschmarks flood Germany and the CID officers try to establish a connection in England, they find themselves facing violent and ruthless opposition from a gang with murder on their minds.
When a successful businessman begins to receive blackmail threats, the squad expect a straightforward case, They discover more than they bargained for and learn that people in high places prove to be bad losers.
Bulman's dedication to duty that he tries to arrest Carmos, a psychopathic killer, during his wedding, The squad must use all their ingenuity to extricate him from the villain's clutches - Bulman is wounded and in danger of dying.