Oedipus asks Tiresias, the prophet, to help Thebes end the plague by guiding him to the murderers of King Laius. But Tiresias does not want to tell Oedipus what he knows. He asks to be sent home and says he will not tell his secret. Oedipus insults Tiresias, but the prophet still refuses to speak.
The blind seer sees the truth, but tries to protect Oedipus by remaining silent. This puts him into conflict with Oedipus, who is merely trying to be a good leader and save his city.
Now angry, Oedipus accuses Tiresias of plotting to kill Laius. This upsets Tiresias, who tells Oedipus that Oedipus himself is the cause of the plague—Oedipus is the murderer of Laius. As the insults fly back and forth, Tiresias hints that Oedipus is guilty of further outrages.
Oedipus, thinking he understands more than he does, is too quick to judge Tiresias. Though Tiresias is a noted seer, Oedipus is too angry to listen to him.
Oedipus convinces himself that Creon has put Tiresias up to making these accusations in attempt to overthrow him. He mocks Tiresias's blindness and calls the man a false prophet. The leader of the chorus tries to calm the two men down. Tiresias warns Oedipus that Oedipus is the blind one—blind to the corrupt details of his own life.
Oedipus, a man of action, describes blindness as an inability to see. Tiresias, the seer, describes it as an inability to see the truth. In calling Tiresias a false prophet, Oedipus shows his willingness to fight against any prophecy he disagrees with.
As the men continue to argue, Tiresias prophesies that Oedipus will know who his parents are by the end of the day, and that this knowledge will destroy him. He leaves with a riddle: the killer of Laius is a native Theban whom many think is a foreigner; he will soon be blind; he is both brother and father to his children; he killed his own father. Both men exit.
The riddle is a reference to the riddle of the Sphinx. Solving that riddle gave Oedipus his fame. Solving this one will destroy him. In other words, Oedipus's own qualities doom him. This riddle is pretty obvious, but Oedipus is not ready or willing to solve it.
The chorus enters, chanting about the murderer of Laius, pursued now by the gods and the words of a prophecy. The chorus concludes that it will not believe the serious charges brought against Oedipus without proof.
The chorus helps the reader and the audience interpret the play. Here, the reader understands that the people of Thebes are still on Oedipus's side. He is still their champion.
Creon enters, upset that he has been accused of treachery. Oedipus enters. He launches further accusations at Creon. Creon tries to defend himself against the charges. He claims he has no idea what Tiresias was going to say, and has no desire to be king. He suggests that Oedipus is being unreasonable and paranoid. Oedipus refuses to listen, and says he wants Creon dead. Jocasta—Oedipus's wife and Creon's sister—approaches.
Creon perhaps protests too much when he says he has no desire to be king (as his actions at the end of the play and in Antigone and Oedipus at Colonus will show). However, he is right that Oedipus is making strong accusations without evidence. Oedipus appears quite unreasonable, overcome by anger and the desire to take some decisive action.