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 Athens. Once they are gone, Caesar breaks his truce, wages war against Pompey, and defeats him. After using Lepidus’s army to secure a victory, he accuses Lepidus of treason, imprisons him, and confiscates his land and possessions. This news angers Antony, as do the rumors that Caesar has been speaking out against him in public. Octavia pleads with Antony to maintain a peaceful relationship with her brother. Should Antony and Caesar fight, she says, her affections would be painfully divided. Antony dispatches her to Rome on a peace mission, and quickly returns to Egypt and Cleopatra. There, he raises a large army to fight Caesar, and Caesar, incensed over Antony’s treatment of his sister, responds in kind. Caesar commands his army and navy to Egypt. Ignoring all advice to the contrary, Antony elects to fight him at sea, allowing Cleopatra to command a ship despite Enobarbus’s strong objections. Antony’s forces lose the battle when Cleopatra’s ship flees and Antony’s follows, leaving the rest of the fleet vulnerable.
Antony despairs, condemning Cleopatra for leading him into infamy but quickly forgiving her. He and Cleopatra send requests to their conqueror: Antony asks to be allowed to live in Egypt, while Cleopatra asks that her kingdom be passed down to her rightful heirs. Caesar dismisses Antony’s request, but he promises Cleopatra a fair hearing if she betrays her lover. Cleopatra seems to be giving thought to Caesar’s message when Antony barges in, curses her for her treachery, and orders the innocent messenger whipped. When, moments later, Antony forgives Cleopatra, Enobarbus decides that his master is finished and defects to Caesar’s camp.
Antony meets Caesar’s troops in battle and scores an unexpected victory. When he learns of Enobarbus’s desertion, Antony laments his own bad fortune, which he believes has corrupted an honorable man. He sends his friend’s possessions to Caesar’s camp and returns to Cleopatra to celebrate his victory. Enobarbus, undone by shame at his own disloyalty, bows under the weight of his guilt and dies. Another day brings another battle, and once again Antony meets Caesar at sea. As before, the Egyptian fleet proves treacherous; it abandons the fight and leaves Antony to suffer defeat. Convinced that his lover has betrayed him, Antony vows to kill Cleopatra. In order to protect herself, she quarters herself in her monument and sends word that she has committed suicide. Antony, racked with grief, determines to join his queen in the afterlife. He commands one of his attendants to fulfill his promise of unquestioned service and kill him. The attendant kills himself instead. Antony then falls on his own sword, but the wound is not immediately fatal. He is carried to Cleopatra’s monument, where the lovers are reunited briefly before Antony’s death. Caesar takes the queen prisoner, planning to display her in Rome as a testament to the might of his empire, but she learns of his plan and kills herself with the help of several poisonous snakes. Caesar has her buried beside Antony.