Came to visit his brother Martin in West Berlin, Susan Mallison (Claire Bloom) meet Ivo Kern (James Mason), a friend Bettina (Hildegard Knef), wife of Martin (Geoffrey Toone). She discovers that the man is the husband of Bettina that it believed dead. Ivo is actually an agent of espionage East who forces his wife to work for him. Its leader, decides to kidnap Bettina Halendar to compel it to surrender one of his friends, Olaf Kastner (Ernst Schröder), head of a network of escape to the West. But agents are wrong and they take Susan. Fell in love with it, Ivo decides to save.