"A young psychiatrist applies for a job at a mental asylum and must pass a test by interviewing four patients. He must figure out which of the patients, is in fact, the doctor that he would be replacing if hired."
Peter Cushing
as Smith
Patrick Magee
as Dr. Lionel Rutherford
Herbert Lom
as Byron
Britt Ekland
as Lucy
Barry Morse
as Bruno
Charlotte Rampling
as Barbara
Barbara Parkins
as Bonnie
Robert Powell
as Dr. Martin
Sylvia Syms
as Ruth
Richard Todd
as Walter
James Villiers
as George
Geoffrey Bayldon
as Max Reynolds
Ann Firbank
as Anna
Megs Jenkins
as Nurse Higgins
John Franklyn-Robbins
as Mr. Stebbins
Roy Ward Baker
Director
Robert Bloch
Writer
Story
Douglas Gamley
Original Music Composer
Denys N. Coop
Director of Photography
Roy Ashton
Makeup Artist
Joan Carpenter
Hairdresser
Clive Smith
Sound Editor
Norman Bolland
Sound Mixer
Ronnie Curtis
Casting
Gustave M. Berne
Executive Producer
Tony Curtis
Art Direction
Milton Subotsky
Producer
Peter Tanner
Editor
Max Rosenberg