The Merry Widow is Hanna Glawari, a citizen of the mythical Balkan kingdom of Pontevedro. Her country’s financial situation is precarious; it is imperative that Hanna’s fortune stay in the country. But Hanna is in Paris, surrounded by many attentive Frenchmen. The scene is a party at the Pontevedrinian Embassy there. The Ambassador, Baron Zeta, fearful that Hanna might marry a Frenchman and deprive Pontevedro of her wealth, does not notice that his young wife, Valencienne, is carrying on a flirtation with an attractive Frenchman, Count Camille de Rosillon. Valencienne, always a virtuous wife, resists Camille’s advances, but not before he has written “I love you” on her fan. Hanna arrives at the gathering and is immediately besieged by admirers. She attributes her popularity, at least in part, to her wealth. The worried Baron confers with his aide, Njegus. Prince Danilo Danilowitsch, a handsome attaché and the ideal Pontevedrinian husband for Hanna, must be summoned to the party. Danilo arrives from Maxim’s, the fashionable restaurant where he spends all his free time in the company of lovely ladies – Lolo, Dodo, Jou-Jou, Clo-Clo, Margot, and Frou-Frou. It seems that Hanna and Danilo are old friends. He once hoped to marry her, but his family considered her unsuitable because she was not an aristocrat. Now, as a wealthy widow, she is extremely eligible, but Danilo is too proud to court her again.

The next day, at a party in Hanna’s house to celebrate the Pontevedrinian king’s birthday, the guests arrive in national costume. Hanna entertains them with a national song, “Vilja’.’ The Baron hears from Njegus that Camille wishes to many Hanna. He feels sure his own wife, Valencienne, can persuade Camille not to marry Hanna, little suspecting that Valencienne herself is the woman Camille really wants. Hanna teasingly urges Danilo to court her, and then the men all sing of their eternal problem, women. Curious about Camille’s affairs, the Baron follows him to the garden pavilion and peeks through the keyhole. Camille is there with a woman whom the Baron cannot see clearly. The woman, we know, is the virtuous but flirtatious Valencienne, who has been persuaded to go there for one last kiss. Hanna quickly slips into the pavilion and takes her place. When she and Camille emerge from the pavilion, they announce their plans to many. Poor Danilo decides to forget his sorrow at Maxim’s among the lovely faces of his lady friends.

A replica of Maxim’s has been set up at Hanna’s house for a party, and the ladies from Maxim’s are present. Danilo soon learns from Hanna that she never intended to many Camille and is satisfied by her explanation that she was protecting Valencienne. Valencienne’s fan has been found in the pavilion, but her honor is vindicated, for she had written on the fan her answer to Camille. “I am a virtuous wife.” As Danilo and Hanna dance to the “Merry Widow Waltz;’ he hesitantly confesses his love for her. When she explains that her fortune will be forfeited on remarriage, Danilo proposes. Hanna happily accepts and then reveals that when she remarries, all her millions will go to her new husband.