Rebecca Winstead, Shirley Temple and her stepfather Henry Kipper, William Demarest, are among a crowd of hopefuls entering a singing contest titled “Little Miss America” that doubles as a promotional campaign for a cereal brand. The first entrant has an unappealing voice, and the second falters under mic fright before she can finish.
To give Rebecca an edge, the ad executive Tony Kent, [Randolph Scott], and the cereal company's head, Cyrus Bartlett, [Paul Harvey], listen on the radio and fall in love with Rebecca's singing. From his office, Tony tells his assistant Orville Smithers, [Jack Haley], that this is the contestant he wants. Misunderstanding Tony’s meaning, Orville sends Rebecca and Henry away. Enraged by the mistake, Tony orders Orville to track Rebecca down, but by the time he acts, Rebecca and Henry have already left the building.
Henry takes Rebecca to Sunnybrook Farm to live with her Aunt Miranda Wilkins, [Helen Westley], after another eviction for non-payment of rent. Rebecca quickly bonds with Aunt Miranda and her cousin Gwen Warren, [Gloria Stuart], and she discovers she loves the rustic life and doesn’t want to leave. She then meets a new neighbor who turns out to be Tony Kent, though neither recognizes the other from their city encounters; Tony, meanwhile, is seen with Lola Lee, [Phyllis Brooks], a singer he’s involved with. Rebecca and Tony become friends, and during a visit, Gwen also stops by; Orville arrives again to claim he’s found Rebecca, but Gwen’s piano-playing reveals Rebecca’s voice. Orville recognizes it and exclaims, “That’s the girl,” saving the campaign. Yet Aunt Miranda opposes Rebecca singing on the radio and forbids it. Rebecca and Gwen devise a plan to transmit the performance from Tony’s home rather than the city studio.
Lola Lee arrives late for rehearsal and realizes Tony has feelings for Gwen. Lola and Orville begin rehearsing “Alone With You” with the orchestra, which evolves into the actual evening performance. Tony’s butler, Homer Busby, [Slim Summerville], helps Rebecca descend from her second-story bedroom but accidentally knocks over the ladder, trapping him in Rebecca’s room.
Miranda hears the broadcast and believes the voice sounds like Rebecca’s, but she assumes Rebecca is still in her room. Homer, rocked by a chair, is discovered by Miranda; he begs forgiveness for missing their wedding 25 years earlier. She forgives him and allows Rebecca to continue to sing, but takes her straight home afterward.
Henry, now with his new wife, pursues guardianship to claim control of Rebecca’s talents and plots to sell her singing contract to a rival company of Tony’s. Tony and Gwen locate Rebecca at the local broadcast station and offer $100,000 for the contract, but the rival executive refuses. When Rebecca attempts to sing, her voice falters, and a doctor diagnoses laryngitis, predicting rest for a year or more. The ad executive tears up the contract and Tony offers Henry $5,000 to yield guardianship to Rebecca’s Aunt Miranda. Henry agrees, and Rebecca reveals that she never really lost her voice. The film closes with Gwen and Tony together, Lola Lee and Orville as a couple, and Miranda and Homer as a pair, while Rebecca performs a military-style dance on stage.
