Jeanne Dante stars as precocious 13-year-old Judy Widdell, a devoted fan of dime-novel detective stories. When a real murder occurs in the vicinity, Judy insists upon playing sleuth, dragging teenaged astronomer Tom Fenton (Kenneth Howell) into her Sherlock shenanigans.
| Actor | Role |
|---|---|
 Jeanne DanteJudy Widdell | Judy Widdell |
 Kenneth HowellTom Fenton | Tom Fenton |
 Martha SleeperNancy Fairbrother | Nancy Fairbrother |
 Alan MowbrayArchibald Fenton | Archibald Fenton |
 Walter CatlettDuffy | Duffy |
 Charles WilliamsKasky | Kasky |
 Margaret IrvingAunt Jessica | Aunt Jessica |
 Murray KinnellMorris | Morris |
 Spencer ChartersGilroy | Gilroy |
 Rollo LloydThe Tramp | The Tramp |