It is several years after Oedipus was banished from Thebes, the city he once ruled. The play begins in the grove of the Furies at Colonus, which is close to and ruled by the great city of Athens. Oedipus is now a sorry sight, blind and hobbled, dressed in rags, led by his daughter Antigone.
The oracle in Oedipus Rex demanded that Oedipus be punished for killing his father and marrying his mother. Now a blind old man in rags who needs his daughter to guide him, Oedipus has been punished for his misdeeds.
Oedipus tells Antigone that acceptance is the lesson taught by his suffering. He then asks Antigone to find a place for them to rest, and wonders where they are. Antigone recognizes Athens in the distance, though she doesn't recognize their precise location. But from the landscape she believes they are on holy ground. They decide to rest.
Oedipus's remarks about acceptance suggest that his suffering has made him a wiser man than he was as the headstrong leader in Oedipus Rex. In his past, he tried to fight the fate ordered for him by the gods. Now he accepts his suffering and his fate.
A citizen of Colonus approaches and demands that they move from their resting place, because it is holy ground, the grove of the Furies. Oedipus responds that this is a sign and that in fact he must not move from this place, which will be his refuge. He asks the citizen to send for the king, Theseus, and promises that if Theseus does Oedipus a small service, great good will come of it. The citizen leaves. Oedipus prays to the Furies. In his prayer, he says that, in the same prophecy in which the god Apollo foretold Oedipus's terrible fate, the god also spoke of the grove of the Furies as a place where Oedipus could rest, and where the last chapter of Oedipus's life would take place.
The Furies were avenging spirits of Greek mythology who punished those, like Oedipus, who broke natural law, such as by committing incest or killing a parent. That this grove is prophesied to be Oedipus's final resting place suggests that through suffering—blindness and banishment—Oedipus has atoned for his actions and has been granted redemption by the Furies and the gods. Also, notice how Oedipus now pays strict attention to the prophecy, rather than trying to fight it.
More citizens (the chorus) come looking for the stranger who has dared to set foot on the sacred ground of the terrible Furies. When Oedipus speaks to them, they tell him he must step out of the grove of the Furies. He does, with Antigone's help, and sits on a rocky area just outside the grove. The chorus ask his name and background. Reluctantly, Oedipus identifies himself. Upon hearing his name, the chorus shrinks back in terror and commands him to leave before he brings ruin to their city.
This scene suggests that Oedipus's fame—or rather, his infamy—was widespread even in his own time. Everywhere he went, he could not escape his outcast status. The citizens of Colonus react to him as a cursed man whose presence may bring misfortune to them if they harbor or help him.
Antigone appeals to the citizens' pity and humanity. Oedipus says they should not drive him out just because of his name. He admits that his acts caused terrible suffering, but says that he committed them unknowingly. He appeals to the honor of Athens as a just city and a protector of the weak. Moved by his speech, the chorus agrees to let the king of Athens decide what should be done.
A rider approaches—it is Ismene, Oedipus's other daughter. Oedipus, Antigone, and Ismene have a heartfelt reunion, and then Ismene delivers her news: Oedipus's two sons are engaged in a power struggle for control of Thebes. The younger son, Eteocles, seized the throne from and exiled the elder son, Polynices. Polynices fled to Argos and now is raising an army to attack Thebes, where Eteocles and Creon rule jointly.
Oedipus's daughters are faithful and loving. But his sons rejected their father after his banishment and are now fighting each other for control of Thebes. The sons's actions are also violations of natural law, and Oedipus himself is proof that such actions are punished by the gods.
Ismene then tells Oedipus the latest prophecies from the oracle: the men of Thebes, who cast Oedipus out, will soon try to bring him back. According to the oracle, Oedipus's presence just outside a city would protect that city. So the Thebans will want him to settle near Thebes, but not within the city itself. Oedipus asks whether the Thebans would give him a proper Theban burial after he died. Ismene reports that because Oedipus killed his own father, they would not. Ismene then adds that Oedipus's sons already know of the prophecy.
By accepting and enduring his punishment, Oedipus seems to have earned more than just forgiveness for his terrible actions—his presence has now become a powerful blessing that can safeguard Thebes. Though Creon and Eteocles are eager to exploit Oedipus's newfound power, they still would refuse to accept him as a Theban citizen after his death.
Oedipus is furious, and promises never to return to Thebes. He vents his rage against his sons, who never tried to rescue him, bring him back, or protect him after his downfall. He praises his two daughters for their devotion to him, but says he will never help his sons. He tells the chorus that if they help defend him against the men from Thebes who will try to take him away, they will gain a savior for their land.
The rage Oedipus displays here resembles the rage he showed as a younger man in Oedipus Rex. Yet his rage now is justified because it is directed at those who have legitimately wronged him. In Oedipus Rex, he raged at the innocent and at the gods.
The leader of the chorus is moved by Oedipus's request. He tells Oedipus the ritual that must be performed to appease the Furies, whose sacred ground Oedipus has stepped on and violated. Ismene exits to visit a nearby spring and perform the proper rituals.
Oedipus again displays his obedience to the gods by having Ismene perform the rites to appease the Furies. He doesn't fear other people and may rage at them, but he does fear the gods.