A miniature submarine is wrecked off the coast of a South American country. John Drake's assignment from British Intelligence is to blow her up. Disguised as a fisherman, Drake races against time to find the submarine before the agents of a foreign power can.
| Name | Type | Role | |
|---|---|---|---|
| Ralph Smart | Writer | ||
| John Roddick | Writer | ||
| Richard Clarke | Guest Star | ||
| Peter Arne | Guest Star | ||
| Brad Dancy | Guest Star | ||
| Nadja Regin | Guest Star | ||
| Peter Sallis | Guest Star | ||
| Ronald Leigh-Hunt | Guest Star | ||
| Rebecca Dignam | Guest Star | ||
| Alec Mango | Guest Star | ||
| Helen Horton | Guest Star | Helen | |
| Charles Frend | Director |