Act I. Egypt, 48 B.C. Giulio Cesare (Julius Caesar) has defeated the forces of his political rival and former son-in-law, Pompeo (Pompey), and arrives on the banks of the Nile in triumph. Cornelia, Pompeo's second wife, begs for clemency for her husband, but Cesare says it will be granted only if the man comes to him in person. Scarcely has he said this than Achille (Achillas), the Egyptian military leader, brings in a casket containing Pompeo's head — a gift from Tolomeo (Ptolemy), the co-ruler, with Cleopatra, of Egypt. Cesare takes the gesture badly and leaves to remonstrate with Tolomeo. Cornelia faints, reviving in the arms of her son, Sesto (Sextus). Curio, Cesare's aide, who wants to marry Cornelia, offers to help her avenge her husband's death, but she spurns him. She bemoans her sorrowful state, for which death offers no relief. Sesto resolves to strike down his father's murderer.
Cleopatra learns from her retinue of Pompeo's murder. Realizing that her brother Tolomeo arranged this in hopes of currying favor with Cesare, she decides she must see the Roman emperor herself to muster support for her position as queen. Tolomeo scoffs at her, but she is determined to use her charms on Cesare. Achille enters with the news that Cesare was angered by the murder of Pompeo, adding that he would gladly do away with Cesare in return for Cornelia's hand. Tolomeo welcomes the idea of being rid of the Roman conqueror.
In his camp, Cesare muses on the fragility of life and fame as he stands before the urn containing Pompeo's remains. Curio introduces "Lidia" — actually Cleopatra in disguise as one of her ladies-in-waiting. As she tells of her tribulations at the hands of the tyrant Tolomeo, Cesare is amazed by her beauty. He excuses himself, leaving Cleopatra to hide as the grieving Cornelia appears and takes up her husband's sword. Sesto stops her, saying that he will avenge Pompeo. Cleopatra steps forth and offers the services of her adviser Nireno, who will lead the way to the guilty Tolomeo.
Tolomeo guardedly receives Cesare at his palace. He plans to have him ambushed, but Cesare suspects treachery. When Achille introduces Cornelia, Tolomeo himself is smitten by her beauty, though he pretends to Achille that the latter may still hope to marry her. Sesto tries unsuccessfully to challenge Tolomeo to combat. When Cornelia scorns Achille's wooing, he sends Egyptian soldiers to arrest Sesto. As she bemoans this latest misfortune, Sesto bids her a dejected farewell.
ACT II. In her palace, Cleopatra tells Nireno to lure Cesare to her rooms by promising news of "Lidia." She withdraws, and Cesare arrives in search of her. He is distracted by the sound of beautiful music, and when Cleopatra appears, singing the praises of Cupid's darts, Cesare is enchanted.
In the harem garden of Tolomeo's palace, Achille continues to plead with the adamant Cornelia. When he leaves, Tolomeo also tries to court her, with the same results. Sesto enters, bent on avenging his father's death.
In Cleopatra's quarters, meanwhile, her idyll with Cesare is disturbed by sounds of conspirators approaching. Revealing her identity, she urges him to flee, but he goes to face his enemies as she prays for his safety.
In Tolomeo's harem, the king sits surrounded by his favorites, Cornelia among them. Sesto rushes in and attempts to stab Tolomeo, but he is subdued by Achille, who announces that his soldiers attacked Cesare, who jumped from a palace window into the sea and is undoubtedly dead. Achille now asks for the promised reward of Cornelia's hand in marriage and is sharply turned down by Tolomeo. Sesto tries to kill himself but is dissuaded by his mother; he repeats his determination not to rest until the tyrant who murdered his father is punished.
ACT III. By the shores of the Mediterranean, sounds of battle denote the clash between Tolomeo's and Cleopatra's armies. Victorious, Tolomeo orders the still-defiant Cleopatra led off in chains. Cesare, having barely survived the fray, pulls himself from the water and prays for news of his beloved. As he leaves, Sesto enters, guided by Nireno, in search of Tolomeo; instead he finds the wounded Achille. To avenge himself on Tolomeo for abducting Cornelia, Achille hands Sesto a seal that will give him command over a hundred armed men in a nearby cave. As Achille dies, Cesare appears and demands the seal, declaring he will save both Cornelia and Cleopatra or die in the attempt.
Guarded by soldiers in Tolomeo's camp, Cleopatra fears that Cesare is dead, shattering her last hopes. She is astonished when he appears and embraces her. As he leads his soldiers off to the conquest, she compares her joy to that of a person rescued from a shipwreck.
In the harem, Tolomeo continues to court Cornelia, but Sesto discovers them and kills him. Cornelia blesses her avenging son.
Cesare and Cleopatra enter Alexandria in triumph. Cornelia presents trophies of the slain Tolomeo to Cesare, who passes them on to Cleopatra, saying he will support her rule. As the two declare their love, the people welcome the return of peace.
-- courtesy of Opera News