Hay que casar al príncipe

Tomson, a financial adviser, is called to the aid of the country of Sylvania by the Grand Duke Constantino, known as "Tino." Tomson refuses to aid Tino until the Duke's son Alexis is married. However, Alexis, a romantic, is not interested in the blue-blooded types that his father has selected for him. Instead he wants fate to intercede. Upon learning this, Tomson plans a wife-hunting trip to Paris, "the beauty mart of the world." Once in Paris, Tomson and Tino find a beautiful woman, Yvette, who, for a price, is willing to get the prince's attention without seeking marriage. A few days later, on her way to the palace, Yvette's car gets caught in a rain storm. Spying a lodge, she runs for help, but exhausted, she collapses into Alexis' arms. When Yvette awakens, Alexis, calling himself Lieutenant Eric Sandro, suggests that she continue her trip to the palace after the rain stops. She agrees, but when her visit exceeds three days, she decides to leave because he is too much of a temptation to her virtue. Alexis is intrigued and they agree to meet when her business at the palace is finished. Tomson and Tino plan for Yvette to meet Alexis at a charity festival the next day. At the festival's casino, the Duke's second son Borio, a spoiled prince, decides to play a trick on his father. Aware of Tino's plans, Borio tells Yvette that he is Alexis, which causes Yvette to flirt openly with him. Borio feigns boredom but agrees to meet Yvette the following day. She goes directly to Alexis' lodge, where he gives her a ring. When Borio sees the ring, he demands to know how she got it. Realizing what his brother has done, Borio exposes the ruse to Yvette, happily adding that a prince is not allowed to marry a commoner. At the officer's club, Alexis overhears Borio relating the sordid details to a large group of men. Yvette confirms that Borio's story is true, and a very confused Alexis seeks the help of his colonel, who advises Alexis to follow his heart even if it means standing up to Tino. Meanwhile, Yvette has informed Tino and Tomson of her and Alexis' love, but Tino is adamant that Alexis must marry a duchess. When it becomes apparent that Alexis plans to follow Yvette back to France, Tino, with Tomson's promise of financial aid, agrees to make Yvette a duchess. Following Yvette's trail in his sportscar, Alexis catches up with her when her car breaks down. She joins him, and as they pull away from her car, they kiss and sing a tribute to their love.