The chorus appeal to their King, Oedipus, to save them from the plague that has swept through the city of Thebes. Oedipus agrees he must do something, and states that he has already sent his brother-in-law, Creon, to consult the Delphic Oracle about what to do. Creon is seen returning to Thebes, and asks Oedipus whether they should discuss what he has learnt indoors, in private, or outdoors, in front of the Theban people. Oedipus tells him they should talk outdoors, and Creon tells him that the prophetess at Delphi said that the murderer of the old King, Laius, must be killed or exiled from Thebes in order for the curse to be lifted. Creon then explains the situation behind the death of Laius to Oedipus.
The chorus ask the gods to save Thebes from the plague.
Oedipus sets out the situation: he, their King, can be trusted because he is “a stranger to this story”. He says that when he finds the murderer, the criminal will only be banished rather than killed, but if he finds out that anyone has hidden what they know then they will be banished as well as the killer. The chorus tell Oedipus that they know nothing, but that they think Oedipus should ask for the help of the renowned prophet Tiresias. Oedipus has already called for Tiresias, and wonders why he has taken so long. Tiresias appears, but refuses to tell Oedipus who the killer of Laius was. Oedipus gets very angry and and accuses Tiresias of working with Creon to take power. Tiresias himself gets angry and accuses Oedipus of being the one who killed Laius and also of an unholy marriage. Oedipus furiously dismisses Tiresias, who leaves.
The chorus wonder who killed Laius. They believe in the words of the seer Tiresias, but also trust their King, Oedipus, who saved their city from ruin.
Creon comes to confront Oedipus. He tries to explain that he doesn’t even want to be king and is happy with his current position but Oedipus doesn’t believe him and continues to accuse him until Oedipus’s wife, Jocasta, appears and asks him to let Creon go. After Creon has left, Oedipus tells Jocasta about the oracle that said he would kill his father and marry his mother, but Jocasta comforts him by telling him about the oracle that she and Laius received: it was said that he would be killed by his son, but they killed their child instead and Laius was killed by a stranger, so the prophecy was clearly false. While telling her story Jocasta mentions that Laius was killed "where three roads meet", which brings back some of Oedipus' memories, and he begins questioning Jocasta about the circumstances regarding the murder. He tells Jocasta that on his way to Thebes he killed a man at the same location Laius died, and that he fears that he himself is the murder. He then demands to question the only surviving witness to the crime, the herald.
The chorus pray that they will always obey the gods and live in moderation.
A Messenger finds Jocasta and tells her that Oedipus's "father", Polybus King of Corinth, has died, and that Corinthians now want Oedipus to become their King. Jocasta finds Oedipus and they are both happy, since this means the prophecy about Oedipus killing his father was false. However, Oedipus is still worried about marrying his mother if he returns to Corinth, since his mother is still alive, but the Messenger assures him that she isn't his real mother anyway. He says that baby Oedipus was found by someone who lives in Thebes, who gave him to the Messenger, who passed him on to the King and Queen. Oedipus asks who the first man was and the Chorus tell him that it is the person he has already called to ask about Laius's murder, the herald. Oedipus questions Jocasta about this but she refuses to tell him anything and says that she hopes he never finds out about who he is. Oedipus assumes Jocasta is being prideful and is worried about being ashamed should Oedipus be of low birth. Oedipus says that he doesn't care about that possibility and wants to find out the truth.
The chorus wonder about the truth behind Oedipus's birth: they hope he was born in Thebes and think he might have been the son of a nymph or god.
The Herald is brought in. He is asked if he recognises the Messenger, and after a bit of prompting he says he does. He then refuses to say any more, before eventually being forced to admit that Oedipus was the son of Laius and Jocasta. Oedipus becomes aware that his prophecy had been fulfilled and, filled with grief, he enters the palace.
The chorus discuss how easily someone's fortunes can change: Oedipus used to be the hero of Thebes but now the citizens wish they had never met him.
A messenger from the palace announces that Jocasta hung herself in her room after realising that she married her own son. Oedipus stormed into her room in a rage, determined to kill her. Once he found her body he took the brooches on her dress and used them to stab his eyes out. Oedipus enters and the chorus ask him why he did this to himself. Oedipus says that while Apollo, god of prophecies, was responsible for his downfall, the killing of his father and his marriage to his mother, it was he alone who was responsible for blinding himself because he couldn't bear to see the consequences of his actions. Creon appears and asks him to return to the palace so that he doesn't pollute the daylight. Oedipus asks Creon for immediate banishment, but Creon says he must first consult the gods and ask them what to do. Oedipus also tells Creon to look after his children and asks to see them one last time. Creon brings his two daughters to see him. After a while, Creon asks him to let go of the children and return inside. The chorus warn the audience not to call someone happy until they have died peacefully, because a person's situation can change so suddenly.
