About Sophocles' play, Antigone
While playwrights always presented three plays at the festivals to honor Dionysus, Sophocles did not present the three plays he wrote depicting the tragedies of the House of Cadmus, or the Theban plays as they are more commonly called, as a trilogy, nor did he write and produce them in order of their content. Had he done so, Oedipus Rex would have been performed first, then Antigone, and finally Oedipus at Colonus. Yet Antigone was the first of the Theban plays; it was performed in 442 B.C.E. Oedipus Rex followed several years later in 429 B.C.E., and finally Oedipus at Colonus came years later. While the Greek audience already knew the story of the House of Cadmus, the modern audience must first understand the story of Oedipus in order to understand the play Antigone.
Oedipus' Story
When Laius, King of Thebes, asked Apollo's oracle at Delphi whether he and his wife, Jocasta, would have a son, the oracle told him they would, but this son would one day kill his father. Thus, after his son's birth, Laius decided he would take no chances, and he pierced and bound the babe's ankles and gave him to a herdsman to expose on Mt. Cithaeron. Yet, once there, the herdsman could not bring himself to abandon the baby; instead he gave the baby to another shepherd from Corinth. This shepherd took the child back to Corinth and gave him to King Polybus and Queen Merope, rulers of that city. Since they had longed for a child themselves, they adopted the baby, naming him "Oedipus" (swollen foot). Polybus and Merope raised Oedipus as their own son, never telling him he was not their natural child.

Mt. Cithaeron
When Oedipus was grown, some companions taunted him, calling him a bastard and claiming he was not the legitimate son of Polybus. Troubled, Oedipus traveled to Delphi to consult the oracle about his parentage. The oracle, however, did not answer his question directly, but instead issued a horrible prophesy: that he would one day kill his father, marry his mother, and have children men would shudder to look upon. Horrified, Oedipus left Delphi, swearing he would never return to Corinth, for he wanted to avoid such a fate. He made his way towards Thebes. At a crossroads, he encountered an entourage led by a haughty aristocrat who refused to make way for him and even struck Oedipus with his staff. In a blind rage, Oedipus struck back. He killed the older man and all his servants except for a lowly herdsman who managed to escape.
Oedipus soon arrived at Thebes, which was suffering terribly from a Sphinx, a monstrous winged lion with the head of a woman, who posed a riddle to all travelers and devoured them when they failed to solve it. So far, no one had correctly answered her riddle. When the Sphinx confronted Oedipus with her riddleWhat animal goes on four legs in the morning, two legs at noon, and three legs in the evening?he solved it with the answer Man, who crawls as a baby, walks on two legs in his prime, and walks with the aid of a stick when old. Devastated, the Sphinx cast herself from a cliff. Thus, Oedipus was welcomed into Thebes as a hero for saving the city. Because Thebes had already received word that their king, Laius, was dead, Oedipus was proclaimed king to replace the slain Laius and he married the queen, Jocasta. When the Theban herdsman finally made his way back to the city, he saw that the man who had killed his master was now king, so he asked to be assigned to outlying fields far from the city, never explaining why he wished to be removed from the household. He also told the city that Laius had been killed by thieves, confirming what they had assumed.

Summary of Oedipus Rex (or Oedipus the King): After many prosperous years during which four children were born to Oedipus and Jocasta, a terrible plague ravaged the population of Thebes. Nothing could reproduce -- no crops, no livestock, no humans. Thebes was doomed if the source of the plague was not found and eliminated. The oracle at Delphi proclaimed that Thebes was harboring the murderer of Laius, and until the murderer was found and punished, the plague would continue. In the play, Oedipus efforts to discover the murderer ultimately reveal that he was the cause of the plague; in seeking to avoid his fate, he had unknowingly killed his real father, married his mother, and produced four children who were also his siblings. When the truth is revealed, Jocasta hangs herself and Oedipus takes her brooch and stabs at his eyes until he can no longer see, claiming he cannot bear to look upon his children's faces to see their condemnation. At the end of the play, Oedipus begs his brother-in-law, Creon, to send him into exile.
Oedipus two daughters, Antigone and Ismene, accompanied him into exile, while his two sons, Eteocles and Polyneices, remained in Thebes, where Jocasta's brother Creon ruled until the boys were old enough to take over the throne. Oedipus spent his final days in the city of Colonus, but before he died, he cursed his two sons for their ill treatment of him before and after he left Thebes. He issued a ringing prediction: that one day each would die by the hand of the other. When the boys were grown, they agreed to rule Thebes alternately. Eteocles ruled first, but at the conclusion of his year of reign, he refused to relinquish the throne to Polyneices. Polyneices, who had married the daughter of the king of Argos, led the Argive army in an assault on Thebes. Thebes repelled the attackers, but in the course of the battle the two brothers killed each other. Their uncle Creon assumed the throne and decreed that Eteocles was to be buried with full honors, but Polyneices was to be left unburied, to rot in the sun and to be eaten by scavengers.
The play Antigone begins the day after the battle. The body of Polyneices (plus all the Argive dead) lies on the battleground. Antigone, who is upset over Creon's order, seeks out Ismene to gain her help in burying her brother . . . .