ACT I

Opening- In Venice, a mass is held at the Convent of Sant Angelo in honor of the new French Ambassador Cardinal de Bernis. Among the church singers and musicians is aspiring priest Giacomo Casanova. In the congregation is Father Balbi who has with him a book of text forbidden by the church. Balbi gives the book to a curious Casanova unseen by the Three Inquisitors present. The mass continues during which the Savorgnan sisters catch Casanova's eye. As the congregation processes out, believing he is still in the possession of the forbidden book, Balbi is accosted by the Three Inquisitors who question him. Meanwhile, Casanova is teaching music to the Savorgnan sisters who soon seduce him. Finding him in bed with the sisters, the Inquisition arrive and defrock him as the Savorgnans flee. He is left shamed with only his violin and book.

Bragadin's Masquerade- In the street, Casanova joins a parade of musicians en route to audition for Senator Bragadin who is forming an orchestra for his masquerade ball. Casanova earns a place as does Manon Balletti, a cellist. At the ball, the orchestra play behind a screen. Despite the arrival of his guests Bragadin is more interested in Casanova. He flirts with Casanova who rejects his advances and decides to gate-crash the party with Balletti. Caught, Bragadin confronts Casanova who leaves in search of Balletti who has disappeared.

Palazzo Bragadin- Outside, Casanova is set upon by Venetian ruffians who rob him and leave him for dead with only his book. Bragadin appears and takes Casanova home where he dresses him in a rich Venetian dressing gown and tends to his wounds. Casanova begins to repsond to his tender advances but they are interrupted when Bragadin suffers a heart attack. Consulting his book, Casanova administers first aid and revives Bragadin twice. Recovered, a grateful Bragadin makes Casanova his heir and presents him as an aristocrat. Casanova's elevated status does not go unnoticed by the Three Inquisitors.

Thanksgiving Mass- At the Convent of Sant Angelo, a mass is said in celebration of Bragadin's recovery, presided over by Cardinal de Bernis. As Casanova leaves, a note from M.M. is passed to him. Meanwhile at Il Piombi, under torture to confess who has the forbidden book, Father Balbi gives up Casanova's name.

Cardinal de Bernis' Apartment- Following the instructions on the note, Casanova arrives at Cardinal de Bernis' luxurious private apartments. M.M. arrives and the two share a sensual feast before making love under the hidden gaze of de Bernis. Suddenly they are interrupted by Bragadin who warns Casanova that the Inquisition is coming for him. Desperate, Casanova flees but he is soon caught and imprisoned in Il Piombi.

ACT II

Bellino and Henriette- Two women, Bellino and Henriette are leading almost parallel lives. Bellino's brother persuades her to dress like him so she can work as a singer too. Elsewhere Henriette is subjected to violent abuse by her husband. She dresses as a soldier and flees, leaving her baby. Both women are now 'men' in search of freedom.

At the Gaming Table- Courtesans ready themselves for a night at a gaming salon where a poorly dressed man, Casanova, attracts attention as he tells the story of his escape from Il Piombi. A hustler, he makes a little money and moves from table to table advising the players on tactics. Madame de Pompadour arrives and in the corner group of soldiers sit, including the disguised Henriette who intrigues Casanova but flees when her husband enters. Observing everything, Madame de Pompadour asks Casanova to be brought over where he tells her the story of his escape. Feeling they are kindred spirits she takes him to Versailles, dresses him in grand clothes and becomes his benefactor. Casanova is now rich, carefree and reckless. He goes from table to table winning and eventually leaves with two ladies of Versailles much to the enjoyment of Madame de Pompadour.

Parties in Paris- Casanova embarks on a series of sexual encounters and decides to throw a party with a groaning table of food. He auditions musicians and amongst them is his old acquaintance Balletti. Bellino, too, earns a place and Casanova, unknowing of her true gender, is perturbed and intrigued by her. A great party ensues but as it comes to a close, Casanova is left on his own. He picks up a book and begins to work – his life is not just about the sensual, he also has a passion for knowledge.

Casanova's Apartment- Casanova poses at his desk while an artist paints his portrait. He is determined to be painted seriously and not as a playboy but Madame de Pompadour arrives and laughs at his pretenses. Even more determined, Casanova sends her away and turns to his writing. Bellino arrives to visit Casanova who shows her his writing and music. She in turn shares the secret that she is a woman and, liberated, Bellino leaves a dejected Casanova. He returns to his writings and works furiously before gathering his papers to take to the printers. Casanova rushes and bumps into Henriette who is still dressed as a soldier. She soon reveals that she is a woman, telling her tragic story. Casanova takes her in, cares for her and they make love. Madame de Pompadour arrives; she has arranged a meeting between Casanova and Voltaire. Knowing he is hiding someone, she assumes it is a woman, but Henriette appears once more dressed as a soldier and an amused Madame de Pompadour leaves with Voltaire. Casanova redresses Henriette as a woman and begs her to wait for him. He rushes off after Voltaire to whom he confidently explains his theory of cubic geometry, only to be mocked.

Despair- In Casanova's absence, Henriette's husband arrives and convinces her to leave with him. Casanova returns to his apartment and finds Henriette has gone with only a letter left behind. Despondent, he attempts to escape into the world of sensuality. He eats, drinks and organizes musicians to return where a party begins and soon evolves into an orgy of sexual abandon. Casanova tries to lose himself in sex until Henriette unexpectedly returns. Seeing in front of her everything she feared about the corruption of men, she throws Casanova's book and quill at him and leaves forever. Desperate, Casanova tries to once more lose himself in sex but is distracted by visions of his past selves and lovers. He goes to throw himself into the abyss but can't quite do it.

The Writer- A single page flutters down and Casanova gathers this along with the book and quill thrown by Henriette. His past selves and lovers all have pages to offer him which he gathers together as the characters of his life dance in his mind. Rescued by his writing, alone, his memories recorded before they are lost to history.