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...
Dr. Mike Vernon
Leader of the Lystrians
Dr. Claire Harland
Brian Carter
The Lystrian
Nurse Lim
Major Muncaster
Lawrence Blackburn
Police Sergeant Draycott
Sister Evans
Barbara Gough
Sister Kelly
Ted
Harry
Morgan
Sergeant Williams
Lloyd
Elaine
Lorry Driver
Old Joe
Telephone Operator
Dundy
