Mark Antony, one of the three rulers of the Roman Empire, spends his time in Egypt, living a life of decadence and conducting an affair with the country's beautiful queen, Cleopatra. When a message arrives informing him that his wife, Fulvia, is dead and that Pompey is raising an army to rebel against the triumvirate, Antony decides to return to Rome. In Antony's absence, Octavius Caesar and Lepidus, his fellow triumvirs, worry about Pompey's increasing strength. Caesar condemns Antony for neglecting his duties as a statesman and military officer in order to live a decadent life by Cleopatra's side.
The news of his wife's death and imminent battle pricks Antony's sense of duty, and he feels compelled to return to Rome. Upon his arrival, he and Caesar quarrel, while Lepidus ineffectually tries to make peace. Realizing that an alliance is necessary to defeat Pompey, Antony and Caesar agree that Antony will marry Caesar's sister, Octavia, who will solidify their loyalty to one another.
Enobarbus, Antony's closest friend, predicts to Caesar's men that, despite the marriage, Antony will surely return to Cleopatra.
In Egypt, Cleopatra learns of Antony's marriage and flies into a jealous rage. However, when a messenger delivers word that Octavia is plain and unimpressive, Cleopatra becomes confident that she will win Antony back. The triumvirs meet Pompey and settle their differences without going to battle. Pompey agrees to keep peace in exchange for rule over Sicily and Sardinia. That evening, the four men drink to celebrate their truce. One of Pompey's soldiers discloses to him a plan to assassinate the triumvirs, thereby delivering world power into Pompey's hands, but Pompey dismisses the scheme as an affront to his honor. Meanwhile, one of Antony's -generals wins a victory over the kingdom of Parthia.
Antony and Octavia depart for...