Wolfgang Stahl, an American spy operating undercover as an SS officer, has fled Germany with Hitler's secret blueprints for the invasion of Russia. As American, British, and German operatives race through war-torn London in search of the spy, bodies begin to pile up and the question arises: Are Stahl and his American contact being played by one of their own? In this game of spy vs. spy, only Sergeant Troy of Scotland Yard will be shrewd enough to uncover the truth.