Act I - The first act opens in the streets of Paris during Mardi Gras with Rene, Count of Luxembourg who has lost his family's fortune. We move to the artist studio of Armand Brissard, who is trying to persuade his girlfriend, Juliette Vermont, to pose for him as Venus. She tells him she will not remove her clothing to be a model for him until they are married. As they are talking a group of artists and models arrive laden with food, which was intended as a still life model, not to be eaten. Juliette expounds on the delicious menu they have before them. The Count of Luxembourg arrives, broke, but still in the Mardi Gras sprit, followed by three gentlemen who would like to speak to him in private. They explain that they work for Prince Basil Basilovitch, a Russian aristocrat, who is in love with the famous opera singer Angèle Didier. He would like to marry her, but because she is a commoner, it is not possible. He is proposing that in return for a payment of a half of million francs, Rene marry her, thus making her Countess of Luxembourg. After three months of marriage he is to agree to a divorce so that he, Basil, can make her his Princess. Two other conditions are that they never set eyes on each other, and that he leaves Paris that evening, assume a new name, and not return until it is time for the divorce. With that agreed upon, Angèle is brought into the studio, and introduced as Paulette, and a painter’s easel is placed as a screen between them. The marriage service is conducted, and when it comes to the exchange of rings a hole is made in the canvas for their two hands to meet. The check is given to Rene before the group leaves and he feels himself deeply in love with the unknown women.

Act II -The scene is the ballroom of Angela’s house, three months since her secret marriage to a total stranger (Count of Luxembourg). The party is a double celebration - her retirement from the stage, and her marriage to Prince Basil. Juliette has become the companion to Angèle, since Brissard left Paris three months earlier with Rene. Having returned to Paris the night before his divorce, Rene decides to attend the opera. He is enchanted with Angela’s beauty and arrives at her home that evening hoping to meet her, not know he is married to her! Brissard has come to, trying to win back his Juliette, which happens after he promises to marry her the next day. Rene’s appearance at the party and Angela’s obvious interest in him greatly disturbs Basil on his arrival. He is fearful she might discover the fact that she is lawfully married to Rene, and having failed to persuade Rene to leave the party, Basil announces ton the guests his forthcoming marriage to Angèle. Brissard protests that Angèle is not free to marry anyone, for she is already married. This forces the Prince and Angèle to make public the facts of the marriage of convenience, and Angèle openly declares her contempt for the man who has thus, by marrying her, sold his name for money. Rene steps forward and admits that he is the Count of Luxembourg, reminding her that he was also helping her on her way to becoming a Princess. He gets ready to leave, but Angèle cannot bear to see him go, realizing the depth of her love for him. She takes her place, as his wife, at his side and they leave the ballroom together.

Act III - The next morning, in the lobby of the Grand Hotel, Rene takes Angèle to his room to discuss the difficulties of their situation. They meet a guest upon their arrival - an elderly woman of eccentric appearance who turns out to be a Princess Stasa Kokozov, recently arrived from Russia. She triumphantly tells them that she had obtained from the Tsar an order commanding her marriage to Prince Basil. Of course, Rene and Angèle are overjoyed at her news. Prince Basil arrives and is frozen in horror in seeing Princess Kokozov. There is no other course open to him but to release Rene from his obligation. Rene pays back the money to him, after finding out some of his family art was worth millions and that poverty is a thing of the past. Brissard and Juliette join them before their upcoming marriage and are reunited with their friends The Count and Countess of Luxembourg!