A man is murdered in a room with no windows and a steel lined door which locks only from the inside.
Bernard Lee
as Superintendent Meredith
David Knight
as Lexman
Francis de Wolff
as Ramon Karadis
Colette Wilde
as Grace
Christine Shaw
as Linda Buckland
Stanley Morgan
as Sergeant Anson
A.J. Brown
as Commissioner of Police
Richard Caldicot
as Fisher
Edmond Bennett
as Manservant
Simon Lack
as Jock
Anthony Baird
as Sergeant Butterfield
Gladys Henson
as Landlady
