While holidaying in Italy, Nick Morell, son of John Morell, a famous English philosopher and amateur musician, becomes friendly with young Guido, and Morell discovers the boy has an extraordinary instinct for orchestration and a phenomenal music memory. A neighboring couple, Signor and Signora Boudini become aware of the boy's talents, and she appeals to his parents to let her educate him musically. Torn by their love for their son and, they feel,the duty to let the world hear his talent, they consent.
| Actor | Role |
|---|---|
 Jeremy SpenserGuido Ferugia | Guido Ferugia |
 Guy RolfeJohn Morell | John Morell |
 Kathleen RyanCatherine Morell | Catherine Morell |
 Kathleen ByronAnne Bondini | Anne Bondini |
 Henry OscarMario Bondini | Mario Bondini |
 Rosalie CrutchleyCarlotta Ferugia | Carlotta Ferugia |
 Ferdy MayneCarlo Ferugia | Carlo Ferugia |
 James Robertson JusticeSir Arthur Harold | Sir Arthur Harold |
 John SlaterDr. Lorenzo | Dr. Lorenzo |
 Christopher LeeNewsman | Newsman |
| HHugo SchusterDr. Freihaus | Dr. Freihaus |
 Robert RiettiGiuseppe | Giuseppe |
| RRobin DowellNick Morell | Nick Morell |
 Michael BalfourLucio | Lucio |
| DDavid McCallum Sr.Leader of orchestra, Royal Albert Hall | Leader of orchestra, Royal Albert Hall |
| DDora HydeLeader of orchestra, Naples | Leader of orchestra, Naples |
| MMichael CroudsonNick's Friend | Nick's Friend |
| DDon LiddelBenjamino | Benjamino |
| BBen WillianCar Driver | Car Driver |
| AAlex FieldsDoorkeeper | Doorkeeper |
| PPenny DaneMaid | Maid |
| LLeonard TrolleyWaiter | Waiter |