Released a year prior to the outbreak of World War II, this espionage thriller taps into the fears and concerns of the time and features imposing screen and stage star as a Naval commander who alone is entrusted with secret information that might foil an enemy invasion. International relations are strained; there is a strong possibility of war and, should diplomacy fail, Britain must be prepared to strike the first, and hopefully decisive, blow. The British Navy is the instrument, and Commander Clive Stanton the man chosen for a special and secret mission. He receives sealed orders as he is about to go ashore to dine with Mrs Maybridge, a local socialite and wife of a retired admiral - unaware that the house has been infiltrated by fifth columnists. Also starring , and comedian .