A young woman from a progressive middle-class family moves to Shanghai with her husband Rolf in the mid-1930s. Although she has a child, she is not prepared to retreat into private life. She meets Dr. Richard Sorge and decides to become a scout. After training near Moscow - she is given the cover name Sonja - she is sent to Manchuria on her first assignment with her comrade Ernst. She has an affair with Ernst and has a child with him. A new assignment that takes her to Poland separates her from Ernst. She is awarded the Order of the Red Banner in Moscow for her work. She then goes to Switzerland and radios information about the impending war to the Soviet Union. She meets Rolf and Ernst, who are on an assignment in the Far East. Sonja marries an Englishman to avoid being extradited to Germany.
