When the play opens, a plague has overcome Thebes, and so Oedipus has sent Creon to consult the oracle of Apollo to seek a solution. Creon reports that the oracle has declared that Laius's murderer must be found and banished from Thebes, only then will the plague be lifted. Oedipus sends for the blind prophet, Teiresias, to tell him who killed Laius. Teiresias names Oedipus as the killer and says that his marriage to Iocasta is sinful, and reminds him of his parents' curse. Iocasta and Oedipus exchange stories of their pasts. Then a messenger arrives announcing the death of Polybus, King of Cornith. Oedipus is relieved believing that he has escaped the prophecy. However, the messenger tells him that it was he who took Oedipus to Cornith. The servant confirms this, and thus the truth is revealed and the prophecy has been fulfilled after all.

Oedipus is an honorable man. He is brave...

His love for his citizens drives him to seek the killer of Laius in order to rid the city of the plague. He is driven to find out his true identity by a culmination of events, the prophet's riddle, the messenger's tale, and Iocasta's account, all of which begin to haunt him.
His flaw is the same as Laius and Iocasta, believing that human actions can outwit destiny. Oedipus is a good man at heart, who only wants the best for his family and his city. And that is why this play is still so appealing to audiences, the fact that bad things can happen to good people. According to logic, Oedipus did everything right. He left Cornith to protect his parents, solved the Sphinx's riddle and saved Thebes, was a faithful husband and devoted father, yet he could not escape his destiny.

Bibliography

Sophocles. Oedipus Rex. http://classics.mit.edu/Sophocles/oedipus.html