Caesar is alone at night in the Egyptian desert, apostrophizing a statue of the Sphinx. Caesar is startled when a young girl, Cleopatra, addresses him from the paws of the Sphinx. He climbs up to her, thinking he is dreaming. She is full of superstitions about cats and Nile water. She tells Caesar she is there because the Romans are coming to eat her people. Caesar sees that he is not dreaming and identifies himself to Cleopatra as a Roman. She is terror-stricken, but Caesar tells her that he will eat her unless she can show herself to him as a woman, not a girl. Cleopatra puts herself in the hands of this Roman and they move to her throne room. Caesar tries to persuade Cleopatra to act like a queen; Ftatateeta enters and begins to order Cleopatra about until the nurse is chased from the room. Caesar orders Cleopatra’s servants to dress her in her royal robes. When Roman soldiers enter and salute Caesar, Cleopatra finally realizes who he is and, with a sob of relief, falls into his arms.
The ten-year-old king Ptolemy is delivering a speech from the throne in Alexandria, prompted by his tutor and guardian. Caesar enters and demands taxes, then calls for Cleopatra. Rufio reminds Caesar that there is a Roman army of occupation in Egypt, commanded by Achillas and supporting the Egyptians, while Caesar has only four thousand men. Achillas and Pothinus suggest that they hold the upper hand, but when Roman troops enter, the Egyptians back off. Lucius Septimius and Pothinus remind Caesar that they decapitated Pompey to ingratiate themselves with Caesar, who is horrified to hear of the act. All the Egyptians but Ptolemy leave, and Rufio again protests against Caesar’s clemency. Ptolemy is escorted out. Cleopatra and Caesar discuss how much Cleopatra has grown, and Caesar promises to send strong young Mark Antony to Cleopatra. A wounded Roman soldier enters to inform Caesar that the Roman army of occupation has come; Caesar orders that all the ships be burned except those that are to carry the Romans to the lighthouse on an island in the harbor. As Caesar starts to arm himself, Pothinus enters, followed by Theodotus with the news that the great library in Alexandria is burning. After Pothinus and Theodotus leave, Cleopatra helps Caesar put on his armor and makes fun of his baldness. Caesar and Rufio leave to lead the troops to the Pharos.