Téo, a private detective, despite the insistence of his fiancee, Sonia, refuses to abandon his dangerous profession and go work with her father, a wealthy industrialist. There's always a new case making Téo postpone a visit to his future father-in-law. This time his is hired by a mysterious woman, who paid him handsomely, to do a job being given only a vague notion of the case. To his surprise, as soon as the woman leaves, Téo is attacked by four men. Recovered from his injuries, Téo begins to investigate the woman who hired him.