Before the play begins . . .
By leaving his home in Corinth, Oedipus thinks he has escaped a terrible prophecy that says that he will kill his father and marry his mother. Oedipus has defeated the riddling Sphinx, saved the seven-gated city of Thebes, and married the queen Jocasta. (Her first husband, Laius, had been killed.) They have four children, Eteocles, Polynices, Antigone, and Ismene, and they rule in peace.
But a mysterious plague has recently afflicted the city, bringing death to the people, livestock, and crops. Oedipus has sent Creon to Delphi to find out from the oracle there what to do.
In the play . . .
A priest and his followers ask Oedipus to find a way to save them from the plague. Creon returns and reports that they need to find the murderer of Laius, the former king. Oedipus swears he will find and punish the man.
He summons Tiresias, the famous seer, to tell what he knows. At first Tiresias refuses to speak, but when pressed, he tells Oedipus that the murderer he seeks is Oedipus himself. The king and the chorus refuse to believe the prophet, and Oedipus accuses Tiresias and Creon of plots and corruption.
Jocasta intervenes and tells Oedipus not to worry. Oedipus starts to asks questions about Laius’s death, and the circumstances begin to sound familiar. But a Messenger comes from Corinth to say that Oedipus’s father is dead, so he doesn’t need to worry about the prophecy. Oedipus asks about his mother, since there’s that other part of the prophecy, and the Messenger tells him he was adopted.
Jocasta realizes the truth—that Oedipus is her son as well as her husband—and tells Oedipus to stop the interrogations. He doesn’t listen, and an eyewitness, the Herdsman who rescued him when he was an infant, confirms that he was Laius and Jocasta’s child, and that Oedipus killed Laius.
A Servant reports the suicide of Jocasta, and Oedipus emerges from the house having blinded himself. He seeks exile and mourns with his daughters. Creon takes over.