A CIA operative enlists the help of his friend, a French secret agent, in locating the source responsible for leaking classified Nato information to Moscow. However, the investigation leads to a Soviet espionage ring operating within the French government and a plot connected to a Cuban rebellion. Alfred Hitchcock's spy thriller, starring John Forsythe, Frederick Stafford, Dany Robin and Roscoe Lee Browne.

Copenhagen, Denmark, 1962. When a high-ranking Soviet official decides to change sides, a French intelligence agent is caught up in a cold, silent and bloody spy war in which his own family will play a decisive role.