The Gondoliersor, The King of Barataria
The contadine (peasant girls) are waiting for the two gondoliers, Giuseppe and Marco, to come and choose their brides from among them. They choose Tessa and Gianetta; and all dance off to the altar.
The Duke of Plaza-Toro (and suite) meanwhile arrive in Venice. Twenty years before, when the Duke's daughter, Casilda, was yet a baby, she and the infant heir to the throne of Barataria were married. Shortly thereafter, the infant disappeared, abducted to Venice by the Grand Inquisitor, Don Alhambra, when the reigning monarch of that land became a despot. Recently, that monarch was killed in an insurrection, and the grand inquisitor is searching for the now-grown prince to take his rightful place on the throne. As a result, the throne of Barataria became vacant; and the Duke wishes to establish Casilda as Queen. He has arrived — accompanied by his wife, daughter, and Luiz, his drummer — in search of his daughter's missing husband.
The Duke tells Casilda about her childhood marriage. Luiz and Casilda (who — unknown to her parents — are in love with each other) accordingly renounce their love. Don Alhambra tells them that the person they are seeking is either Giuseppe or Marco; he is not sure which. He will send for the nurse who took care of the infant prince and she will be able to tell which one it is. Meanwhile, Giuseppe and Marco are to go to Barataria at once and rule jointly until the matter is straightened out. Tessa and Gianetta must remain behind, with the vague promise from Don Alhambra that they may later join their husbands, and with the idea that one of them will then be Queen.
In Barataria, Giuseppe and Marco are attempting to be kings of a country where they have declared everyone equal, with mixed results. On the whole, things are going well, except for the fact they miss their wives. Suddenly Tessa & Gianetta appear, having made the trip in spite of Don Alhambra's injunction.
Don Alhambra points out the weaknesses of Giuseppe's and Marco's system of government. When he learns that Tessa and Gianetta are there, he is disturbed, and tells them about the prince's infant marriage. This revelation is a heavy blow to the hopes of Tessa and Gianetta; for not only is neither of them to be Queen, but also one of them is actually not married at all. Meanwhile, the Duke and his family arrive in Barataria to present themselves to the Kings. The Duke adds his criticism of Giuseppe's and Marco's court, and attempts to teach the joint rulers some court etiquette.
The woman who had been the nurse of the baby prince when he was married to Casilda arrives, and discloses who is the rightful King of Barataria....