In ancient Rome, in the aftermath of a famine, the common people, or plebeians, demand the right to set their own price for the city's grain supply. In response to their protests, the ruling aristocracy, or patricians, grant the plebeians five representatives, or tribunes--a decision that provokes the ire of the proud patrician soldier Caius Martius, who has nothing but contempt for the lower classes. At this time, war breaks out with a neighboring Italian tribe, the Volscians, who are led by Martius' great rival, Tullus Aufidius. In the campaign that follows, the Volscians are defeated, and the Rome takes the Italian city of Corioles, thanks to the heroism of Martius. In recognition of his great deeds, he is granted the name Coriolanus.

Upon his return to Rome, Coriolanus is given a hero's welcome, and the Senate offers to make him consul. In order to gain this office, however, he must go out and plead for the votes of the plebeians, a task that he undertakes reluctantly. At first, the common people agree to give him their votes, but they later reverse their decision at the prodding of two clever tribunes, Brutus and Sicinius, who consider Coriolanus an enemy of the people. This drives the proud Coriolanus into a fury, and he speaks out intemperately against the very idea of popular rule; Brutus and Sicinius, seizing on his words, declare him a traitor to the Roman state and drive him into exile.

Desiring revenge against Rome, Coriolanus goes to his Volscian enemy, Aufidius, in the city of Antium, and makes peace with him. Aufidius is planning a new campaign against the Romans, and he welcomes Coriolanus's assistance, although he soon feels himself to be falling into his new ally's shadow. Their army proceeds to march on Rome, throwing the city into a panic--Rome's armies are helpless to stop the advance, and soon Aufidius and Coriolanus are encamped outside the city walls. Two of his oldest friends come pleading for mercy, but Coriolanus refuses to hear him. However, when his mother, Volumnia, to whom he is devoted, begs him to make peace, he relents, and the Romans hail Volumnia the savior of the city. Meanwhile, Coriolanus and the Volscians return to Antium, where the residents hail Coriolanus as a hero. Aufidius, feeling slighted, declares that Coriolanus's failure to take Rome amounts to treachery; in the ensuing argument, some of Aufidius' men assassinate Coriolanus.