Maurice Legrand, a meek cashier and aspirant painter, is married to Adèle, an abusive woman whose former husband Alexis Godard had died during
World War I. Maurice attends a company celebration, and as he leaves, he sees a man named André "Dédé" Jauguin hitting Lucienne "Lulu" Pelletier, a prostitute, on the street. Lulu hits him back in defense as Maurice approaches them. He learns they are waiting a taxi ride, and accompanies them. After Dédé is dropped at his residence, Maurice walks Lulu home. Along the way, she reveals that Dédé is actually her pimp, having known him for three years. Maurice returns home and is questioned by Adèle why he has arrived late; she also degrades his paintings, as she complains they are cluttering their apartment. One month later, Maurice has rented an apartment for Lulu, whom he takes as his mistress, and decorates the apartment with his paintings since Adèle intends to throw them away. One night, Maurice and Lulu are alone together until he sees her apartment lights are on. Lulu returns to her apartment, where Dédé has arrived. He takes the paintings and schemes to sell them claiming they were painted by Lulu using an American alias "Clara Wood". Several weeks pass, and Maurice is directed by his employer to an art store where he sees his paintings on display. At her apartment, Lulu deceives Maurice into claiming that she and her fictitious brother had sold the paintings to Wallstein. The paintings become a success with the art critics, and Dédé and Lulu become affluent. Sometime later, Maurice stumbles upon Adèle's former husband Alexis, who had supposedly died. Alexis explains at a café that during the war, he was falsely reported as dead after he had switched identification cards with another soldier to escape his marriage to Adèle. He was then captured by the Germans as a prisoner of war and served time in prison before he was released. Now penniless, Alexis asks Maurice for one thousand francs, which Maurice knows Adèle has hidden in her wardrobe. Maurice arranges to have Alexis steal the money as he falsely claims he and Adèle will attend a theatre tomorrow night. The scheme succeeds in Maurice's favor as Adèle calls the police, whom Maurice informs that Alexis is indeed alive. As a free man, Maurice goes to Lulu's apartment, but discovers she and Dédé are in bed together. He leaves in shock, but returns in the morning to talk to Lulu. She confesses that she loves Dédé and humiliates Maurice, saying that the only reason she stayed with him was his money. Maurice stabs her with a knife and leaves the apartment with no witnesses. Lulu is later found dead, and Maurice and Dédé are questioned. The interrogator releases Maurice due to his lack of a criminal history. Dédé is charged with Lulu's murder owing to his reputation, and is found guilty and executed. Maurice is accused of mishandling 2500 francs by his employer, and is fired under the guise for having health problems. Maurice roams the street as a vagrant, and reencounters Alexis who informs him that Adèle had died. As a car transports Maurice's self portrait, Maurice and Alexis obtain 20 francs off the street and walk off. ==Cast==