A medical doctor gets into trouble when one of his patients turns out have been involved in espionage (maybe).

Robert Avranche, a middle-aged, alcoholic garage owner, is sitting on a train, reflecting on the emptiness of his life. An attractive young woman, Donatienne, suddenly enters the compartment and offers to make love to him. Robert accepts but, when the woman leaves the train afterwards, he decides to follow her...

The day he is released from jail, Serge is expected by four killers sent by Count Charles Varèse assigned to make him confess where he has hidden the jewels stolen during his last stickup. On the other hand the police inspector who arrested him offers him protection on condition he gives him the same piece of information. Serge refuses and is about to be tortured by Varèse's henchmen when Michel, a friendly hood, comes to his rescue. His friendship will result in... a heap of corpses!
—Guy Bellinger