In turn-of-the-century Paris, middle-aged film director Emile Clément divides his time between making movies and romancing young women. When his best friend Jacques, a handsome, young actor, becomes despondent because his girl friend has left him for a wealthy man, Emile coaches him in the art of flirtation and lovemaking. Later, Emile learns that music hall entertainer Célestin, an old friend whose now-deceased wife was once Emile's lover, has recently lost his sister and is going on tour, leaving his daughter to fend for herself. The next day, a saddened Emile says goodbye to Jacques, who has to leave Paris to complete his Army service. Upon returning home that night, Emile is approached by a young woman, who introduces herself as Célestin's daughter Madeleine. Although Madeleine reveals to Emile that her mother often spoke of him in loving terms, Emile sends her away, instructing her to return in the morning. Instead of leaving, Madeleine plants herself outside Emile's house, and when she starts to walk off with a strange man, Emile rushes out to retrieve her. Emile invites her to spend the night, and later, realizing that she is a naïve country girl, insists that she move in with him and his housekeeper. Emile then sets out to protect Madeleine from all men and orders his film crew to guard her like their daughter. During a music hall performance one evening, Emile puts his arm around Madeleine to discourage the advances of an admirer and finds himself enjoying the unplanned intimacy. Later, an unsuspecting Madeleine breaks into tears, telling Emile that she is depressed because men are not attracted to her. Emile reassures her, but does not express his romantic feelings for her. The next day, at a sidewalk café, Emile questions Madeleine about her future husband, and she insists that a man's age is not important to her. Now completely in love, Emile throws himself into his filmmaking and is thrilled when Jacques shows up at the studio one afternoon. Upon leaving that evening, Jacques, still dressed in his military clothes, spies Madeleine boarding a streetcar and, unaware of her relationship with Emile, pursues her. Using Emile's seduction techniques, Jacques romances Madeleine all night and finally confesses his love. Madeleine has also fallen in love with Jacques and makes plans to see him again the next night. At the studio the following day, both Madeleine and Jacques are surprised to discover that they are playing opposite each other in Emile's latest "desert" romance. Jacques, who has told Emile about the "wonderful girl" he met the night before, then learns from the crew that Emile is in love with Madeleine. Not wanting to hurt his friend, Jacques tries to stand Madeleine up, but the unsuspecting Emile insists that he meet her as planned. After Madeleine confesses that she had indeed been planning to marry Emile, Jacques demands that they stop seeing each other. A heartbroken Madeleine then learns from Emile that her father is soon returning to Paris. At the studio the next day, Madeleine and Jacques attempt to reunite but are stopped by the ever-vigilant crew. When the crew insists that Jacques inform Emile about his relationship with Madeleine, Jacques confesses all to his friend. Emile is furious at Jacques and stunned when Madeleine moves out of his house to return to her father. Later, Emile runs into a drunken Jacques at a café and, no longer angry, commiserates with him. Upon returning home, Emile discovers Madeleine waiting for him, having been snubbed by her father. Madeleine tearfully asks Emile to marry her, but he refuses her. On the set the next day, as a visiting sultan watches, Madeleine and Jacques play a scene together in which they both commit suicide because the vizir character whom Madeleine's character is being forced to marry refuses to give her up. When the sultan objects to the unhappy ending, Emile realizes that youth belongs with youth and, not only changes the film's ending, but gives his blessing to Jacques and Madeleine as well.