Hippolytus is the bastard son of Theseus. He has decided to honor the goddess Artemis and spurn Aphrodite and Aphrodite is not pleased. (This is a theme with Greek gods and goddesses.) In response, she has cursed Phaedra, the wife of Theseus so that she is in love with Hippolytus.
Phaedra confess this love to her nurse in strict confidence but Hippolytus finds out. He is sicked and scornful:
Great Zeus, why didst thou, to man's sorrow, put woman, evil counterfeit, to dwell where shines the sun? If thou wert minded that the human race should multiply, it was not from woman they should have drawn their stock, but in thy temples they should have paid gold or iron or ponderous bronze and bought a family, each man proportioned to his offering, and so in independence dwelt, from women free.He has sworn not to tell but he leaves in anger. After he is gone, Phaedra, in despair, commits suicide. She leaves a note that blames Hippolytus, claiming that he has defiled her. Theseus arrives home to find all of this. In his anger, he makes a plea to Poseidon:
O father Poseidon, once didst thou promise to fulfill prayers of mine; answer one of these and slay my son, let him not escape this single day, if the prayers thou gavest me were indeed with issue fraught.To sum up, Theseus has lost his wife and has no called on the gods to kill his son. Hippolytus returns and Theseus accuses him of the crime. Hippolytus hotly claims his innocence but Theseus will have none of it. He orders his son out of the kingdom, to be forever exiled.
While he is leaving, Poseidon sends a huge wave to kill him. Attendants bring his broken body back to Theseus. The truth comes out and they forgive each other before Hippolytus dies.
I'm not sure what to make of this story. It's absolutely filled with injustice. Both Paedra and Hippolytus are (essentially) killed by the gods. I guess there is some lesson in that Hippo should have been more respectful of Aphrodite but the penalties here seem rather stiff.
I know that Aristotle wrote in response to Euripides, arguing that theater should have clear morals. I'm guessing that he wouldn't have cared for this at all.