For Sophocles's play, ''Oedipus the King'', the synopsis of the story would be somewhat like this:
As the play opens, Oedipus is the popular ruler of Thebes. The kingdom is suffering from plague and on consulting the Oracle at Delphi, Oedipus learns that the plague will end only when the murderer of Queen Jocasta's first husband is found and punished. Oedipus determines to find out, and he ultimately finds out that the old man he himself killed when he first came to Thebes, had in fact been the Queen's husband and the old king. He also finds out the terrible truth that the old king, Laius, had been his own father, and that Jocasta was his mother; that he has been living in incest with her and produced offspring by her too. This shame drives Jocasta to suicide and Oedipus to blind himself, and go off in lonely exile.
This is the essential, very basic summation, or synopsis. I trust its helpful.