A safecracker turns double agent during WWII.

British safecracker Eddie Chapman is arrested during the early part of World War II for robbing a movie theater and imprisoned on the Isle of Jersey. When the Germans occupy the island, he contacts two members of German Intelligence, Colonel Steinhager and The Countess, and offers himself, for a price, as a spy. His offer accepted, Eddie receives espionage training from Baron von Grunen, and after passing a loyalty test, he is parachuted into England. Once there, he volunteers to work for British Intelligence in exchange for a full pardon. When the British stage a fake explosion of an aircraft factory which is photographed by German reconnaissance planes, Eddie is credited for the sabotage and returned to Paris to be awarded the German Iron Cross. Then, as the Allies approach Paris, Eddie is sent back to England to report on the accuracy of Hitler's rocket attacks on London. Instead, he radios false reports and diverts the rockets into unpopulated areas. Now a hero in both countries, Eddie celebrates the war's end in a London pub. As he sips his beer, the temptations of his former life return to him and he surreptitiously eyes the tavern safe.