Based on the play Only a Dream by Lothar Schmidt, George Cukor and Ernst Lubitsch directed this musical comedy about a happily married couple who flirt with affairs.
Run out of a park by Paris police, Dr. André Bertier (Maurice Chevalier) and his wife Colette (Jeanette MacDonald) happily sing, "What a little thing like a wedding ring can do." Colette has invited over her best friend Mitzi (Genevieve Tobin). Her husband professor Olivier (Roland Young) has hired a detective to follow her. She shares a taxi in the rain with André, but he gets out to avoid suspicion. Mitzi chats with Colette, saying when one is not well-mated, marriage can be over-rated. André comes in and discovers he has already met Mitzi.
Pretending to be sick, Mitzi calls for a doctor, and André reluctantly leave his wife to go. He sees Mitzi, mixes a tonic, and drinks it, as they sing "Three Times a Day." Adolph (Charles Ruggles) calls Colette to tell her he is coming to her dinner party as Romeo, but she informs him it is not a costume party. (His butler wanted to see him in tights.) Colette catches André switching the place cards and suspects Mademoiselle Martel. While jealous, she flirts with Adolph. The title song "One Hour with You" is sung by Mitzi to André, by Adolph to Colette, and by Colette and André to each other. André follows the mischievous Mitzi into the garden, and Adolph tells Colette that only his education keeps him from acting like an animal. Colette sees André with Martel and cries. Mitzi tells André she has a taxi waiting; he says goodnight and locks the door. Colette jealously calls André a liar, and so he goes out. Colette finds Adolph downstairs, and he kisses her before she shows him out.
After the detective makes his report, Mitzi moves out. Colette talks in her sleep and says she dreamed about Adolph; but André just laughs. The professor visits André and reads the detailed report of how André was with Mitzi until 4:44 a.m. He asks André to be a witness in his divorce suit. André turns to the audience and sings, "I Ask You, What Would You Do?" André confesses to Colette that he is the one breaking up Mitzi's marriage. She hits him and says she wants a divorce. Then Adolph comes in and confirms that he kissed Colette. Colette tells André they are even. They talk to the audience and then kiss happily.
This story affirms a happy marriage while titillating the audience with affairs as another marriage breaks up. André is almost too charming for his own good, and Colette's jealousy actually pushes her husband into an assignation. Yet in the end the strength of their love for each other triumphs.