Based on an operetta with music by Sigmund Romberg and lyrics by Oscar Hammerstein II, a princess falls in love aboard ship with a heroic lieutenant.
Princess Tanya (Grace Moore) leaves a bridge game to listen to gypsy music from below. She asks Lt. Michael Petroff (Lawrence Tibbett) to translate the words to a risqué song he sang even though she understands Gypsy. They drink champagne, and he kisses her. She is invited to sing in first class and asks him to join her in the duet "Wanting You." Her uncle Count Igor (Roland Young) tells his wife he married her, because he thought she had money. Tanya agrees to meet Michael at 11 on the last night of the Caspian Sea voyage.
At Krasnov Tanya tells Michael to see her at the governor's residence, as Governor Boris Brusiloff (Adolphe Menjou) announces his engagement to Tanya. At a tavern Michael sings "Lover Come Back to Me." At the ball Boris dances with Tanya, and Igor tells her to get the money if she is going to marry for it. Boris believes a fiancé not having a husband's privileges is obsolete; but Tanya disagrees. Tanya sings Boris a love song; but he's not sure it's meant for him. Uninvited Michael dances with Tanya and wants to take her away, while Igor occupies Boris. Tanya tells Boris that Michael has returned her lost bracelet, and Boris rewards him with money and appointment to the fort at Darvaz, where they kill their officers. Boris announces his wedding to Tanya, and Michael sings "Women" about betrayal.
As Michael is riding toward Darvaz, a blinded captain comes out of the fort and falls off a cliff. Michael asks who is in command and shoots those who say they are. When one says, "You are," everyone laughs. Boris says they will obey or be shot for treason. A car arrives, and Tanya hits Boris with her riding whip. Igor refuses to leave before the Turkoman attack until it is too late. Tanya tells Michael he is the finest man she ever knew, and they are married by a priest. Michael gives her a pistol and commands his men. He leads a surprise night attack, asking in song for "Stout-hearted Men." In a fierce fight with swords and guns, Michael is shot. The next morning Boris arrives with reinforcements. One survivor reports all the rest are dead. Boris honors Michael, and Tanya tells Boris she loved him. Tanya sings to the soldiers, "Lover Come Back to Me," and Michael and his men return.
Innuendo pervades this film as Igor encourages the lovers. Yet the Russian lieutenant's only wedding present for the princess is a pistol. The excellent music and Igor's wit overcome an otherwise violent story.