Laius and Jocasta receive the Oracle of Delphi, which states that any son born of Laius is prophesized to murder him and marry his wife, thus becoming the new King of Thebes.
Laius sends a herdsman to abandon Oedipus in the mountains, but takes pity upon the baby and gives him to a passing stranger; who happens to be the messenger of King Polybus of Corinth.
Oedipus becomes aware of his prophecy but believes the victims are Polybus and Merope. He sets off to Thebes, where he gets into an argument with an old traveler at a crossroads, and kills the man.
A plague has been destroying Thebes. Oedipus sends Creon to Apollo to find how to end the plague, and is told that the murder of King Laius needs to be avenged, blood for blood.
Oedipus suspects the prophecy has come true and comes in contact with the messenger who explains Polybus' death. They then find the Herdsman who tells the whole story confirming that Oedipus is the son of Laius and Jocasta.
Learning this information, Jocasta commits suicide. Oedipus gouges his eyes out so he can't "see" anymore. Oedipus asks Creon, the new king, to banish him to the mountains.