An heiress has to say no to every question for 24 hours if she wants to star on Broadway.

When teenagers Lynne and Richard dress up in their parents' clothes from the 1920's for the amusement of some friends, their uncle, J. Maxwell Bloomhaus, chides them for making fun of their parents. He tells them what it was like for people in 1929 after the stock market crashed: In 1929, Max is the guardian of his niece Nanette Carter's fortune. Because of his bad investments, Nanette's fortune is lost in the crash. The stagestruck Nanette, who is unaware of her loss, is being pestered by theatrical producer Larry Blair to back a show written by Jimmy Smith and Tommy Trainor. To help convince her, Larry brings Jimmy and Tommy to Nanette's house, where he pretends that Jimmy needs the money from the show to pay for his sister's operation. Tommy and Jimmy play her some songs from the show, and despite the misgivings of her secretary, Pauline Hastings, Nanette agrees to back the show. Jimmy then suggests that Nanette play the lead, replacing Larry's girl friend, Beatrice Darcy. That night, Nanette asks Max to sell some of her securities. Not wanting to tell her that he sold her securities long ago, Max agrees to give her the money on condition that she say "no" to everything for forty-eight hours. When Nanette's negative responses to some of Larry's questions drive the other backers away, Nanette invites the entire cast to rehearse at her house over the weekend. Trying to force Nanette to break her promise, Max compels her to deny that she likes the play and the songs. He then learns from his lawyer, William Early, that he might be able to save some of the lost fortune if he can sign certain papers before ten o'clock, but after Nanette is stopped for reckless driving, her negative answers to the policeman's questions lands them both in jail. Later, Max encourages Jimmy to propose to Nanette, but even though she loves Jimmy, Nanette does not say "yes." Having lost his bet, Max is forced to tell Nanette the truth. Larry returns the show to Tommy, who suggests they raise the money themselves. Pauline uses her feminine wiles to convince Early to back the production, now called No, No, Nanette , and it is a success. Pauline and Early get married, as do Nanette and Jimmy. Max finishes his story just before Nanette and Jimmy return home to their children.