Fantômas is a man of many disguises. He uses maquillage as a weapon. He can impersonate anyone using an array of masks and can create endless confusion by constantly changing his appearance.

Roland Lasserre is a shy boy, which would be nothing if he weren't also prone to the violent tantrums that have earned him his nickname "Soupe au lait". It's when Francine announces her engagement that he decides to declare his love for her. Francine is not at all keen on the husband her parents are forcing on her - a wealthy record manufacturer - but she gives in under their pressure and asks Roland to give her up. But fate has other plans. A car accident provokes the young man's anger, and with Francine on board, he chases after the hit-and-run driver and ends up in a ditch, luckily undamaged, 50 km from Paris. Torrential rain, lack of transport, welcoming hostelry. All Roland and Francine have to do is confess their guilt, and for the sake of honor, get married... All would be well were it not for René, the neglected fiancé, who provokes "Soupe au lait" and triggers a scandal during the ceremony.

On this beautiful May 1st, Thérèse is about to give birth. Their presence at home is undesirable, so Jean, her husband, decides to take François, their little boy, to a soccer match. Their plans change when they meet a former factory mate who seems to have made a success of his life. This man, Blanchot, decides to return to Jean a sum of money he had once borrowed. Trusted, Jean is drawn into a clandestine circle, where his apparent luck delivers him without ulterior motive to Blanchot, who is one of the ringleaders. The police interrupt the dangerous game, putting Jean, who has no identity papers, in an awkward situation.

Cochu, a peasant, is the whipping boy of his regimental comrades. He is called "buffer of the capiston", that is to say the captain's order. But he finds himself in the service of Hortense, the captain's sister.