In this tense espionage drama set in 1942, William Holden plays Eric Erickson, an American-born Swede who is put on the Allied blacklist for trading oil with the Nazis. Collins (Hugh Griffith), a British intelligence agent, offers to expunge Erickson's name from the blacklist after the war in return for information on the Nazis. Erickson agrees to the plan and proceeds to make it look as if he is pro-Nazi. This subterfuge causes him to be branded a traitor, and his wife, believing Eric to be a Nazi, walks out on him. Nevertheless, Eric continues with his deceit and makes the Germans think that he is planning to construct an oil refinery in Sweden to serve as a fuel supply for Germany. As a result he is allowed entrance to four German oil refinery, and he passes on the information to Collins. But Eric is being put under surveillance by the Nazis. They discover that Eric's lover, Marianne (Lilli Palmer) is working for the Allies. Suddenly both Marianne and Eric are arrested and thrown into Moabit Prison -- with dire consequences for both of them.