Starring Jean Arthur and Marlene Dietrich, A Foreign Affairis a cynical satire that mirrors the bewildering moral climate of the late 1940s. Phoebe Frost (Arthur), an upright Republican member of Congress, travels to Berlin to look into reports of corruption among the occupying American forces. She enlists an army captain (John Lund) in her crusade and finds herself falling for him, unaware that he is the man romantically involved with a German cabaret singer Dietrich) who can lead army investigators to a high-level Nazi war criminal.