Sophocles begins by describing a procession of priests who come before the sacred altar outside the palace to lament over the plague that has befallen the city of Thebes. The priests hope that the gods will show mercy to Thebes and take back their curse. Soon Oedipus, seeing himself as the peoples' agent of salvation, enters to reassure his people.
Oedipus has been the king of Thebes for many years now. As alluded to in Sophocles' introduction, the Thebans make him king after he rescues them from the Sphinx, an evil being who possesses supernatural power. To save the city, Oedipus correctly answers the Sphinx's riddle: what creature walks on four feet, then two feet, and finally three feet? The answer that Oedipus gives is man.
Though Oedipus is not a god, the people of Thebes regard him highly for his bravery and intelligence. The temple priest exemplifies this regard when he implores Oedipus to help the city: You cannot equal the gods, your children know that, bending at your altar. But we rate you first of men, both in the common crisis of our lives and face-to-face encounters with the gods. He goes on to kneel before the king and beg for his assistance.
Oedipus, the obliging father figure, willingly pledges to find and root out the cause of Thebes' curse. In fact, he says he's already taken action on behalf of Thebes, sending Creon to Delphi to learn what Apollo's oracle says.
Just as Oedipus wonders out loud why Creon has taken so long to return, the priest sees the queen's brother approaching and Creon soon enters. Though Creon wishes to speak to Oedipus inside the palace in private, the king instructs him to reveal the oracle of Apollo in public, in front of the priests and townspeople. Obligingly, Creon says that the plague of the city is due to the unresolved murder of King Laius, the former husband of Jocasta and the Theban king who reigned before Oedipus. According to Creon, the city's curse will only be removed when justice is dealt to Laius' murderer.