Sophocles 
Oedipus the King [EPUB ebook] 

A priest and the chorus of Thebans arrive at the palace to call upon their King, Oedipus, to aid them with the plague. Oedipus had sent his brother-in-law Creon to ask help of the oracle at Delphi, and he returns at that moment. Creon says the plague is the result of religious pollution, caused because the murderer of their former King, Laius, had never been caught. Oedipus vows to find the murderer and curses him for the plague that he has caused.