Of Sophocles’s three Theban plays that have survived and that deal with the story of Oedipus, Oedipus Rex was the second to be written. However, in terms of the chronology of events that the plays describe, it comes first, followed by Oedipus at Colonus and then Antigone.
Prior to the start of Oedipus Rex, Oedipus has become the king of Thebes while unwittingly fulfilling a prophecy that he would kill his father, Laius (the previous king), and marry his mother, Jocasta (whom Oedipus took as his queen after solving the riddle of the Sphinx). The action of Sophocles’s play concerns Oedipus’s search for the murderer of Laius in order to end a plague ravaging Thebes, unaware that the killer he is looking for is none other than himself. At the end of the play, after the truth finally comes to light, Jocasta hangs herself while Oedipus horrified at his patricide and incest proceeds to gouge out his own eyes in despair.