Routine tests on a traffic accident victim lead to shocking discoveries when the man's blood is found to be unidentifiable and x-rays reveal a disc embedded in his brain. His fabulous tale of being an escaped prisoner from an alien spaceship takes a turn for the sinister when the hospital staff realise that they're under a state of siege...
Edward Judd
as Dr. Mike Vernon
Yoko Tani
as Leader of the Lystrians
Valerie Gearon
as Dr. Claire Harland
Lyndon Brook
as Brian Carter
Ric Young
as The Lystrian
Tsai Chin
as Nurse Lim
Barrie Ingham
as Major Muncaster
Anthony Sharp
as Lawrence Blackburn
Glyn Houston
as Police Sergeant Draycott
Ann Castle
as Sister Evans
Jean Lodge
as Barbara Gough
Ann Martin
as Sister Kelly
