The episode has been observed by Barnaba, who, when all the others save Enzo have entered the church, goes up to him and, despite his disguise as a sea captain, addresses him by his name and title, "Enzo Grimaldo, Prince of Santa Fior."
The spy knows the whole story. Enzo and Laura were betrothed. Although they were separated and she obliged to wed Alvise, and neither had seen the other since then, until the meeting a few moments before, their passion still is as strong as ever. Barnaba, cynically explaining that, in order to obtain Gioconda for himself, he wishes to show her how false Enzo is, promises him that he will arrange for Laura, on that night, to be aboard Enzo's vessel, ready to escape with him to sea.
Enzo departs. Barnaba summons one of his tools, Isèpo, the public letter-writer, whose stand is near the Lion's Mouth. At that moment Gioconda and La Cieca emerge from the church, and Gioconda, seeing Barnaba, swiftly draws her mother behind a column, where they are hidden from view. The girl hears the spy dictate to Isèpo a letter, for whom intended she does not know, informing someone that his wife plans to elope that evening with Enzo. Having thus learned that Enzo no longer loves her, she vanishes with her mother into the church. Barnaba drops the letter into the Lion's Mouth. Isèpo goes. The spy, as keen in intellect as he is cruel and unrelenting in action, addresses in soliloquy the Doge's palace. "O monumento! Regia e bolgia dogale!" (O mighty monument, palace and den of the Doges).
The masquers and populace return. They are singing. They dance "La Furlana." In the church a monk and then the chorus chant. Gioconda and her mother come out. Gioconda laments that Enzo should have forsaken her. La Cieca seeks to comfort her. In the church the chanting continues.
Act II. "The Rosary." Night. A brigantine, showing its starboard side. In front, the deserted bank of an uninhabited island in the Fusina Lagoon. In the farthest distance, the sky and the lagoon. A few stars visible. On the right, a cloud, above which the moon is rising. In front, a small altar of the Virgin, lighted by a red lamp. The name of the brigantine—"Hecate"—painted on the prow. Lanterns on the deck.
At the rising of the curtain sailors are discovered; some seated on the deck, others standing in groups, each with a speaking trumpet. Several cabin boys are seen, some clinging to the shrouds, some seated. Remaining thus grouped, they sing a Marinaresca, in part a sailors' "chanty," in part a regular melody.
In a boat Barnaba appears with Isèpo. They are disguised as fishermen. Barnaba sings a fisherman's ballad, "Ah! Pescator, affonda l'esca" (Fisher-boy, thy net now lower).
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