Three kids get mixed up with jewel thieves and stolen diamonds in a 24-hour road rally.
| Actor | Role |
|---|---|
 Peter FirthRobert 'Bobby' Stewart | Robert 'Bobby' Stewart |
 George SewellHenry Stewart | Henry Stewart |
 Patrick AllenInsp. Cook | Insp. Cook |
 Derek NewarkMercer | Mercer |
 Dudley SuttonFinch | Finch |
 Barry JacksonWheeler | Wheeler |
 Christopher MalcolmJock | Jock |
 Edwin RichfieldNot listed | Not listed |
 Richard WattisSir Hilary Stanton | Sir Hilary Stanton |
 Ambrosine PhillpottsLady Truesdale | Lady Truesdale |
 Allan CuthbertsonGus Ashley | Gus Ashley |
 Arthur HewlettBenjy | Benjy |
 Spencer BanksCharlie Todd | Charlie Todd |
| CCynthia LundSusan Stewart | Susan Stewart |
 Candace GlendenningElizabeth (uncredited) | Elizabeth (uncredited) |
 Robin LangfordPeter Pitt | Peter Pitt |
 Tom BowmanNot listed | Not listed |
 John SavidentSteward | Steward |
| MMark EdwardsWhiteman | Whiteman |
| PPatrick McAlinneyJunkman | Junkman |
 Andrew McCullochBilly | Billy |
 George WoodbridgePC Andrew | PC Andrew |
 Patrick HoltSteward | Steward |
| MMaggie HanleyMrs. Maggie Stewart | Mrs. Maggie Stewart |
 George InnesInsp. Timothy | Insp. Timothy |