A couple on holiday in Haiti become involved in a series of savage murders linked to a doctor's new invention, a drug with extreme side effects.
| Actor | Role |
|---|---|
 Anthony SteffenDoctor Williams | Doctor Williams |
 Anita StrindbergGrace Wright | Grace Wright |
 Gabriele TintiFred Wright | Fred Wright |
 Umberto RahoPhilip | Philip |
 Stelio CandelliGarner | Garner |
 Kathryn WittRobin | Robin |
| AAlfio NicolosiPeacock | Peacock |
| GGordon FelioNot listed | Not listed |
| RRichard OsborneNot listed | Not listed |
| BBob LemoineNot listed | Not listed |
| PPierre Richard MerceronNot listed | Not listed |