Angel stars Marlene Dietrich as Maria, the neglected wife of Sir Frederick Barker (Herbert Marshall), a British diplomat who travels often and seems little concerned with his spouse. Maria has nearly reached her breaking point when she travels to Paris to visit her old friend Anna Dmitrivena (Laura Hope Crews), a Grand Duchess who also operates an exclusive bordello. While in Paris, Maria meets Anthony Halton (Melvyn Douglas), a visitor from America who seems quite taken with her. While Maria enjoys Anthony's attentions, she backs off and retreats to England. Shortly after her return, Maria and Frederick attend the races and she spots Anthony in the crowd. Maria is tempted to continue her romance with Anthony (who now realizes that she's married), while Frederick begins to wonder if his wife might be growing restless.