An American tourist and a troubled young woman are chased by her gang leader brother to a top secret British government facility that conducts experiments on children.
| Actor | Role |
|---|---|
 Macdonald CareySimon Wells | Simon Wells |
 Shirley Anne FieldJoan | Joan |
 Viveca LindforsFreya Neilson | Freya Neilson |
 Alexander KnoxBernard | Bernard |
 Oliver ReedKing | King |
 Walter GotellMajor Holland | Major Holland |
 James VilliersCaptain Gregory | Captain Gregory |
 Tom KempinskiTed | Ted |
 Kenneth CopeSid | Sid |
 Brian OultonMr. Dingle | Mr. Dingle |
 Barbara EverestMiss Lamont | Miss Lamont |
| AAllan McClellandMr. Stuart | Mr. Stuart |
 James MaxwellMr. Talbot | Mr. Talbot |
| RRachel ClayVictoria | Victoria |
| CCaroline SheldonElizabeth | Elizabeth |
| RRebecca DignamAnne | Anne |
| SSiobhan TaylorMary | Mary |
 Nicholas ClayRichard (as Nicolas Clay) | Richard (as Nicolas Clay) |
| KKit WilliamsHenry | Henry |
| CChristopher WittyWilliam | William |
| DDavid PalmerGeorge | George |
| JJohn ThompsonCharles | Charles |
| FFiona DuncanControl Room Guard (uncredited) | Control Room Guard (uncredited) |
| LLeón GarcíaTeddy Boy (uncredited) | Teddy Boy (uncredited) |
| VVictor Gorf(uncredited) | (uncredited) |