After their parents die in a road accident, a strongly moral young woman named Thérèse Voise leaves a convent shortly before taking her vows in order to care for her younger sister Denise and run the family stationery shop with her. Thérèse is very protective of Denise and becomes concerned when her sister strikes up an acquaintance with Max, a young amateur boxer and Automobile repair shop mechanic. Max is a self-centered, amoral drifter who is conducting numerous different relationships with girls at nightclubs. He is also pursuing Irène Faugeret, a wealthy married woman, managing to get employment as her chauffeur and become her lover. Max strikes up a friendship of sorts with Biquet, a bellhop at the Hôtel Carlton who acts as Max's eyes and ears, especially as concerns Madame Faugeret.