Final answer:
At the beginning of the play Oedipus Rex, the city of Thebes is plagued by a mysterious illness. Oedipus, the king, sends his brother-in-law to seek advice at the oracle of Delphi to find a remedy for the plague. The oracle reveals that the city's suffering is a result of the unsolved murder of the previous king, Laius.
Step-by-step explanation:
At the beginning of the play Oedipus Rex, the city of Thebes is suffering from a terrible plague that is causing widespread death and sickness among its people. In order to find a solution to the plague, Oedipus sends his brother-in-law, Creon, to consult the oracle of Delphi.
The oracle reveals that the only way to end the plague is to find and punish the killer of the previous king, Laius. This sets off a chain of events as Oedipus takes on the task of uncovering the truth and bringing the killer to justice.