Directed by Roy Del Ruth. With Nelson Eddy, Ris Stevens, Nigel Bruce, Florence Bates. Maria and Karl Lang are the singing duo of Vienna. Maria is very flirtatious and Karl very jealous. Karl decides to masquerade as a Russian guardsman and attempts to make Maria flirt with him - to test her loyalty to him - as the Russian, Karl makes a vigorous attempt to seduce Maria. For a moment she accepts then rejects. Karl is left in turmoil…