Six-year-old "Mike" goes to live with her pregnant older sister, Babs, who plays string bass in José Iturbi's orchestra. And the orchestra is rapidly turning completely female, what with the draft. As the orchestra travels around the country, Babs' fellow orchestra members intercept and hide her War Office telegram to protect the baby.
| Actor | Role |
|---|---|
 Margaret O'BrienMike | Mike |
 José IturbiJosé Iturbi | José Iturbi |
 June AllysonBarbara Ainsworth | Barbara Ainsworth |
 Jimmy DuranteAndrews | Andrews |
 Marsha HuntRosalind | Rosalind |
 Hugh HerbertUncle Ferdinand | Uncle Ferdinand |
 Harry DavenportDoctor | Doctor |
 Marie WilsonMarie | Marie |
 Larry AdlerLarry | Larry |
 Ben LessyKickebush | Kickebush |
 Connie GilchristTravelers Aid Woman | Travelers Aid Woman |
| KKatherine BalfourElsa | Elsa |
 Helen GilbertHelen | Helen |
 Madeleine LebeauJane (as Madeleine LeBeau) | Jane (as Madeleine LeBeau) |
 Ethel GriffiesMrs. McGuff | Mrs. McGuff |
 Mary ParkerAnita | Anita |
| EEddie JacksonSinger | Singer |
| JJack RothDrummer | Drummer |
 Willie BestRed Cap (uncredited) | Red Cap (uncredited) |
 Bess FlowersConcertgoer (uncredited) | Concertgoer (uncredited) |
 Byron FoulgerMr. Perkins (uncredited) | Mr. Perkins (uncredited) |