Alicia Huberman (Ingrid Bergman) gains notoriety when her father, a Nazi spy is convinced of treason against the US following World War II. At a party thrown soon after, Alice meets a handsome stranger named Devlin (Cary Grant) who reveals after a clash of wits and temperament that he is a U.S. Intelligence Agent.
Because she has fallen in love with the dashing FBI Agent, Alicia is persuaded into helping Devlin trap and catch Nazi mastermind Alex Sebastian. The more she gets involved in her work, the more at risk she becomes...