En videnskabsmand er forfærdet over en stjålen atombombes destruktive kræfter og truer med at detonere den, medmindre regeringen stopper sit atomvåbenprogram.

Professor John Malcolm Francis Willingdon
Superintendent G.W. Folland
Goldie Phillips
Ann Willingdon
Stephen Lane
Mrs. Emily Georgina Peckett
Arthur Lytton, the Prime Minister
Mrs. Willingdon
Station Policeman
Woman in Phone Box
Army Mechanic
Man on Bus (uncredited)