Former East German engineer Erich Becker had been lured to West Germany by promises of a high reward. Now residing in Stockholm, he is recalled to serve as a spy in the East. He is to convince Dr. Jadenburg to flee from the GDR with the help of his daughter Hanna, who works for the West. While travelling on the train with Hanna, he is told that he is also to murder another agent who betrayed and now works for the Stasi. The traitor is revealed to be a former friend of Becker, Harry Korb.