As with many Greek tragedies, the action of the play is determined by a curse handed down across generations after an important founder of the family has offended the gods. In the case of the Theban plays, Lauis raped a young man, violating the laws of hospitality, which began the curse (Zeus, god of strangers, is responsible in Greek myth for hospitality). Lauis' own son was prophesied to murder his father, and thuis Lauis gave his son Oedipus over to be exposed on the mountainside. Instead, Oedipus was brought to Corinth and raised as the child of its rulers. Suspecting he was adopted, Oedipus inquires of his parentage from the DElphic oracle and is told that he is destined to kill his father and murder his mother. He leaves Corinth to avopid this fate and on the road to Thebes accidentally kills his father. He next solves the riddle of the Sphynx and is given his mother in marriage as a reward.
At the opening of the play no one knows that Jocasta and Laius were Oedipus' parents. IOnstead, they know only that the gods have punished the city with a plague because the killer of Laius caused the city to become ritually polluted. Oedipus, who does not know tht Laius was the old man he killed. summons Tiresias to help him find the murderer of Laius and end the ritual pollution.
Some of the better discussions of this work are to be found in Aristotle's Poetics and Kitto.