Octavius Caesar (later known as Augustus), Mark Antony, and Lepidus form a triumvirate to rule the Roman Empire. Antony will rule in the east and goes to Egypt, where he becomes the lover of Queen Cleopatra. When Pompey raises an army to fight the triumvirate, Antony returns to Rome and marries Caesar's sister, Octavia. Cleopatra becomes jealous and plans to win Antony back. Caesar breaks a deal with Pompey and defeats him. Antony sends Octavia home to Rome and goes back to Cleopatra, and in Egypt he raises an army and a navy to fight Caesar. Antony's forces lose a critical sea battle when Cleopatra's ship flees. Antony hears Cleopatra has committed suicide and falls on his own sword. Cleopatra is taken prisoner and kills herself.