One evening, professor André Barret sees the author of a murder in the darkness; cafe owner Cordelec is the victim. From then on, his suspicions fall on one of his students who had just arrived in his class, Bernard Cormiere.

A young opera dancer tries to help her mother financially by performing in a dubious cabaret.

During the Occupation, a boarding school in Moulins was placed under the rule of a headmistress committed to collaboration. It is within these walls that Michel, Arthur and Franck, escaped prisoners seeking to cross the demarcation line, find themselves stranded. Three boarders, Manouche, Jo and La Tigresse, discreetly devote themselves to them. Until the day when, aware of the danger, they alert the Resistance through the intermediary of a warden. The three men cross into the free zone, and Michel promises to find Manouche.

Micheline, who fled to Paris with the man she is in love with, finds herself on her own when he abandons her. She lands in a reformatory from which she manages to escape.