Oedipus, The King by Sophocles

While Thebes was under the rule of LAIUS and JOCASTA there appeared a strange and monstrous creature, "the riddling Sphinx," "the She-Wolf of the woven song," who in some unexplained way sang riddles of death and slew the people of Thebes. LAIUS went to ask aid of the oracle of Delphi, but was slain mysteriously on the road. Soon afterwards there came to Thebes a young Prince of Corinth, OEDIPUS, who had left his home and was wandering. He faced the Sphinx and read her riddle, whereupon she flung herself from her rock and died. The throne being vacant was offered to OEDIPUS, and with it the hand of the Queen, JOCASTA.

Some ten or twelve years afterwards a pestilence has fallen on Thebes. At this point the play begins.