Soldiers in a rural English town are being brutally murdered by an unknown creature. Two nearby sisters realise they might understand what's happening.
| Actor | Role |
|---|---|
 Beryl ReidEllie Ballantyne | Ellie Ballantyne |
 Flora RobsonJoyce Ballantyne | Joyce Ballantyne |
 John HamillAlan Marlow | Alan Marlow |
 Tessa WyattNurse Sutherland | Nurse Sutherland |
 T. P. McKennaDet. Chief Sup. Paddick | Det. Chief Sup. Paddick |
 Vernon DobtcheffNewsmith | Newsmith |
 John KellandSgt. Young | Sgt. Young |
| DDavid DodimeadDr. Spencer | Dr. Spencer |
 Christopher ChittellBaker | Baker |
| PPeter CrazeRoy | Roy |
| DDafydd HavardStephen Ballantyne | Stephen Ballantyne |
| GGail LidstoneYoung Ellie | Young Ellie |
| EElizabeth ChoiceYoung Joyce | Young Joyce |
| MMerlin WardYoung Stephen | Young Stephen |
 Anthony HeatonAnderson | Anderson |
| AAnabel LittledaleGloria | Gloria |
| HHoward RawlinsonYoung Soldier | Young Soldier |
 Roberta ToveyPaper Girl | Paper Girl |
| RReg LeverAmbulance Man | Ambulance Man |