In Oedipus Rex, the plot begins with the people of Thebes facing a plague on the land. The oracle claims that the plague will end when the murderer of King Laius is found and punished. Oedipus, as king, cares about his subjects. He is the first to exclaim that he will see to it that King Laius' murderer is found, vowing to curse and drive out the murderer.
The prophet Tiresias is summoned. He wishes to say nothing until Oedipus makes him angry by accusing him because of his silence. In anger, Tiresias blurts out that Oedipus is the pollution in the land.
A messenger comes to tell that the King of Corinth is dead. Believing this to be Oedipus' true father, the prophecy stating that Oedipus will kill his father is proved wrong. But the messenger adds some disconcerting news:
The messenger tells him that Polybos was not his father and that he, a shepherd, had been handed the child Oedipus by another shepherd, one of Laius's men. Jocasta tries to intervene and stop the revelations...
As Jocasta begins putting the pieces of the puzzle together, she can not bear the thoughts of being married to her own son. She hangs herself.
Oedipus blinds himself with the pins from her dress. He is led away into exile. The plague is stopped.