Englishman A. J. Fothergill (Robert Donat) is recruited by Colonel Forrester (Laurence Hanray) to spy on Russia for the British government because he can speak the language fluently. As "Peter Ouranoff", he infiltrates a revolutionary group led by Axelstein (Basil Gill). The radicals try to blow up General Gregor Vladinoff (Herbert Lomas (actor)), the father of Alexandra (Marlene Dietrich). When the attempt fails, the would-be assassin is shot, but manages to reach Peter's apartment, where he dies. For his inadvertent involvement, Peter is sent to Siberia.