Act l – The Pontevedrian Embassy in Paris
The Pontevedrian Ambassador, Baron Mirko Zeta, is hosting a gala evening at his residence in Paris in celebration of the Grand Duke’s birthday. Pontevedrian expatriates, prominent Parisians and foreign diplomats mingle. Among the Parisians are the Vicomte Cascada, Raoul de St Brioche and Camille de Rosillon, who amuse themselves by pursuing the Embassy wives. Camille, in particular, is smitten with Baron Zeta’s own wife, Valencienne. She resists his advances – for the moment.

Meanwhile, there is great anticipation at the imminent arrival of the beautiful and vivacious Pontevedrian Hanna Glawari, recently left a wealthy widow after the sudden death of her elderly husband. Baron Zeta, desperately contemplating the impending bankruptcy of Pontevedro, has hatched a plan to keep the widow’s millions in the
country. Excited by the prospect of this brilliant diplomatic coup, he instructs his secretary, Njegus, to fetch the dashing but impecunious First Secretary of the Embassy, Count Danilo Danilowitsch. Zeta hopes that Danilo will sweep Hanna off her feet and marry her, thus securing her millions on behalf of the Fatherland. What Zeta has not counted on is the significant history between Hanna and Danilo.

The Merry Widow herself finally makes a stunning entrance, to the delight of all her prospective admirers. After admonishing them goodnaturedly for being more dazzled by her millions than by herself, she invites all present to attend a traditional Pontevedrian celebration at her villa the following evening. Meanwhile, Valencienne finds herself sorely tempted by the attentions of Camille, and so encourages him to marry the widow as a remedy to their infatuation.

When Danilo still hasn’t made an appearance by midnight, Njegus admits to Baron Zeta that he has been located, surrounded by charming dancers and somewhat the worse for wear, at his favourite nightspot, Chez Maxim. Finally Danilo arrives, only to encounter Hanna under less than ideal circumstances. In their conversation, it is revealed that although they were once in love, she was the daughter of a poor tenant farmer and not wealthy enough for his family to accept her. Halfteasingly, she challenges him to admit that he still has feelings for her. Full of pride, he refuses.

Baron Zeta, however, appeals to Danilo’s sense of patriotic duty and receives from him a promise that even though he will never consent to marry the widow himself, he will actively discourage all foreign contenders. When all the eligible men descend to beg for Hanna’s hand in the Ladies’ Choice dance, she perversely bestows the honour on Danilo. He, in turn, offers to sell it back to the indignant suitors at
a premium, successfully warding them off as the strains of the waltz swirl irresistibly around the couple.

Act ll – The garden of Hanna's villa, the following evening
A sumptuous display of nostalgic folksong and lively dance opens the scene, as the guests are drawn into the spirit of the occasion. Hanna herself entertains the guests with a wistful legend about a beautiful but elusive forest nymph, ‘Vilia’. Danilo, at first conspicuous by his absence, arrives in time to hear Baron Zeta’s newest information: that Camille de Rosillon appears to be the chief threat to Pontevedro’s claim on Hanna’s millions, following the discovery of a lady’s fan on which ‘I love you’ is written in Camille’s hand. Feeling sure that the fan belongs to one of the Embassy wives, he resolves to use it as evidence to undermine Camille’s ambitions towards the Merry Widow. Although Njegus has guessed the real object of Camille’s affections, he keeps silent when Danilo is given instructions to gather intelligence. A lively septet ensues as the Embassy men, with Cascada and St Brioche, bemoan the endless frustrations of keeping their wives and mistresses happy.

Hanna and Danilo reminisce about their courtship in a playful duet. Hanna finds the infamous fan, guessing that its inscription was written by Danilo and intended for her. Predictably, Danilo is stubbornly unable to confess his love for her in words, even though the couple becomes caught up in a romantic waltz.

Realising Camille is about to be surprised by Zeta during a farewell rendezvous with Valencienne in the summerhouse, Njegus quickly enlists Hanna to step in and save the situation. When Hanna is’discovered’ inside with Camille, Zeta is at first relieved and then dismayed as she announces her engagement to the Frenchman. Danilo, jealous and confused, embarks on a tale intended to shame and wound her, and leaves in disgust. Hanna triumphantly realises that he does love her after all, whilst around her all the guests erupt in a congratulatory chorus.

Act lll – The garden of Hanna's villa, later that evening
For Danilo’s entertainment, Hanna has transformed the garden of her villa, with Njegus’ help, into a replica of Maxim’s, complete with its can-can dancing grisettes. When Danilo arrives, he cannot conceal his delight. He presses Hanna in desperation to abandon her plans of marriage to Camille, if only for the sake of the Fatherland. She reveals that she went to the summerhouse only to save the reputation of
another woman – a married one – and assures him that she has no intentions of marrying Camille. Danilo is about to confess his feelings to her when he remembers the one issue which still lies between them – her money.

Baron Zeta, now convinced that Valencienne is having an affair with Camille, announces that he will divorce her in order to marry Hanna himself. Hanna demurs, informing him that under the conditions of her late husband’s will she will lose all her money if she remarries. Overjoyed, Danilo is finally able to declare his love and immediately asks for her hand in marriage. Hanna accepts, and then explains that
the reason she would lose her fortune is that it will become the sole property of her husband!

For Zeta, there is still the vexing matter of the fan, but Valencienne is able to show him what she had written on the reverse side, thus proving herself – now, as ever – ’a highly respectable wife’. General rejoicing follows as all agree that there will always be mystery and intrigue in matters of the heart.