A CIA agent is used as a pawn in an insane woman's plan to steal a Polaris submarine.
| Actor | Role |
|---|---|
 Bette DavisMadame Sin | Madame Sin |
 Robert WagnerAnthony Lawrence | Anthony Lawrence |
 Denholm ElliottMalcolm De Vere | Malcolm De Vere |
 Gordon JacksonCommander Cavendish | Commander Cavendish |
 Dudley SuttonMonk | Monk |
 Catherine SchellBarbara | Barbara |
 Pik-Sen LimNikko | Nikko |
 Paul MaxwellConnors | Connors |
 David HealyBraden | Braden |
 Alan DobieWhite | White |
 Al ManciniFisherman | Fisherman |
 Roy KinnearHolidaymaker | Holidaymaker |
 Charles Lloyd PackMr. Willoughby | Mr. Willoughby |
 Frank MiddlemassDr. Henriques | Dr. Henriques |
 Arnold DiamondLengetti | Lengetti |
 Burt KwoukScarred Operator | Scarred Operator |
 Paul YoungNaval Driver | Naval Driver |
| JJack WeirChief Officer Petty | Chief Officer Petty |
| GGerard NormanLt. Brady | Lt. Brady |
| SStuart HoyleNaval Officer | Naval Officer |
| SStuart McGuganSailor | Sailor |
| IIain AgnewBoat Owner (as Ian Agnew) | Boat Owner (as Ian Agnew) |
 Gabriella LicudiNun | Nun |
 John OrchardRevolutionary | Revolutionary |
| JJohn SlavidRevolutionary | Revolutionary |
| TTina SimmonsGuest (uncredited) | Guest (uncredited) |