Fifteenth-century Venice. The scene is the house of Simone Trovai, military commander of the Venetian Republic. It is the night of the great Carnival, and the lagoon is bathed in the light of torches and fireworks; revelers are heard singing the blasphemous Carnival Song: “From their graves arise the dead to dance… ” Matteo, a young soldier hopelessly in love with Violanta, Simone’s beautiful wife, is mocked by the other soldiers and the serving maids. Simone storms in, dispersing the crowd and ordering the soldiers back to their posts. His rage is aggravated by the fact that no one knows where Violanta is to be found. She has been melancholy and in no sense a wife to Simone ever since her sister Nerina, having been seduced by Alfonso, the Prince of Naples, committed suicide. Since then Violanta has been bent on vengeance.

Giovanni Bracca, a fop, enters in high spirits and tries to take Simone off to the Carnival. He is reluctant to go until he hears that Alfonso is there. As Trovai and Bracca are about to leave, Violanta appears, her hair in disarray and covered with confetti. She calmly orders Bracca to leave and then explains how she went to the Carnival in search of Alfonso, enticed him away from his admirers by singing the Carnival Song and, without revealing her identity, arranged an assignation at Simone’s house, where she intends to have her husband murder Alfonso. Simone is horrified at this plan, not the least because Alfonso, as Prince of Naples, could one day become his commanding officer. But Violanta is maniacally resolved to avenge her dead sister. She tempts her husband with promises of the resumption of marital privileges after the murder. Fired with jealousy and passion, Simone concurs, and they agree on a plan. Simone will remain concealed until Alfonso is disarmed; Violanta will sing the Carnival Song as a signal that Simone should enter and strike the final blow. Simone retires, and Violanta is left alone.

Barbara, Violanta’s old nurse, enters. Surprised at her mistress’s agitation, Barbara tries to soothe Violanta by singing a familiar lullaby. The nurse departs, leaving Violanta alone. Alfonso draws near. From his boat, he sings a serenade to the accompaniment of a lute. When he enters Violanta’s chamber, he continues to praise her great beauty, exhorting her to sing again the song that brought them together. He begins to sing the song himself, but she stops him with the explanation that it will be the last song he will ever hear. At once, she reveals her true identity and her intention to avenge Nerina. He interrupts her to explain the course of his life: his lonely childhood and the hopeless mixture of transitory joys and permanent despair that is his present existence. A longing for death is therefore no stranger to him; he asks her to give the signal and let the deed be accomplished quickly. Violanta finds herself unable to utter a word. Alfonso realizes that she indeed loves him and has from the moment she first saw him. Burning with shame, she bemoans the living death that she must now endure-a wife and yet unfaithful, in love with her own sister’s seducer. He implores her to forget the past and the future and to think only of the present moment of ecstasy; they fall into each other’s arms and sing of the sublimity of pure love.

Their bliss is interrupted by Simone, who, growing impatient, calls out to his wife. Violanta recognizes the end of a dream and sings the fateful song with hysterical abandon. Simone rushes in to find the lovers locked in an embrace. Alfonso declares that Violanta has not deceived her husband because they were never truly together. In a frenzy, Simone tries to stab him, but Violanta interposes herself and receives a mortal wound. Revelers are heard singing the fateful Carnival Song, and Violanta, singing of the purity she is to attain, dies in Simone’s arms.