Jules Maigret, a meticulous Parisian police detective, is a famous literary character. In this film adaptation of his stories, he's trying to solve a murder of a friend, a P.I. who was looking into an industrialist and his family.

A 'machinegunner' (West Country slang for a debt-collector) turns amateur sleuth, but finds himself in hot water with local criminals.

A psychiatrist plots to murder his wife so he can be with his mistress, but his wife mysteriously disappears before he can carry out his plan.

A reporter who needs cash for his son's operation is paid by a smuggler to take a murder rap.