At the urging of his over-protective father, André Carel, a young bourgeois from Paris, travels to Lake Geneva to rejuvenate his health. There, he falls in love with Reine, the beautiful daughter of a simple boatsman. In order to impress her solely through his personality and character, he conceals his wealthy origins and, disguising himself as a migrant laborer, takes up work on board her father's ship.

This is the romanticized story of Louise de Bettignies, who was a spy and heroin of the First World War. In October 1914, in Roubaix, Geneviève de Vandeville delivers mail in secret. Brilliant and effective, she is soon contacted by the Intelligence Service who asks her to lead a team of spies. Geneviève, who is responsible for delivering intelligence from dangerous regions, enlists the help of Maria, a young girl who becomes her friend. Maria and her lover ask Geneviève to plan their escape into Holland. This mission will prove fatal for Geneviève. She is detected by the German counterespionage, arrested, and imprisoned in Brussels. She becomes sick and dies in prison before the war ends. Some time later, Maria and her lover pay their respects to the monument in effigy of Louise de Bettignies.

Marthe, a robust peasant, is a single mother. For her child to be happy, she abandons him to the Duchemin household, eager for an impossible motherhood. Later, the young man is still unaware of the obscure sacrifice of his real mother.

On the advice of his impressario, the singer André Soral resumes his former job as a sailor. He falls in love with Pola, the daughter of the owner of the barge, whom he marries after many adventures.