"Senior officials in the British, American and Russian governments all receive the same cryptic and unsigned message - "I Can Destroy The Sun". What can it mean?"
Maurice Denham
as Dr. Lunn
John Robinson
as Lloyd Crichton
Robert Ayres
as Boardman
Leslie Sands
as Superintendent Travers
Jan Conrad
as Igor Petrov
John Barron
as Henry Walpole
Robert James
as James Cartright
Jennifer Wright
as Mary Harkness
Paddy Webster
as Helen Dawson
Carmel McSharry
as Bella
Jimmy Sangster
Writer
Wilfred Eades
Director
Sydney Newman
Producer
Voytek
Production Design