The play begins when the goddess Aphrodite appears and explains that she has grown angry. Hippolytus, she explains, the bastard son of Theseus, has devoted himself too fully to virginity and the goddess Artemis, and arrogantly rejects the power of sexuality and desire. As a result, Aphrodite says, she has caused Phaidra, Theseus’ wife and Hippolytus’ step-mother, to grow madly in love with Hippolytus, which sets the tragic course of events into motion.
As if to confirm Aphrodite’s judgment of Hippolytus’ character, a servant sees Hippolytus honoring the statue of Artemis and urges him to honor Aphrodite as well. Hippolytus arrogantly denounces the servant and Aphrodite at once. After Hippolytus exits, the palace is stirring because Phaidra suffers – she will not eat, is nearing death, and refuses to explain what her illness could be. Her nurse urges her to tell the truth, and eventually elicits Phaidra to confess that she has been overwhelmed by sexual desire for Hippolytus, an ailment that she treats like a terrible disease. The nurse expresses shock and disgust, but then urges Phaidra to remain calm while she goes into the palace to put together a magical potion that will cure Phaidra’s desire.
Even though Phaidra’s greatest fear was that the truth of her terrible desire would spread, ruining her reputation, the nurse finds Hippolytus and, after having him swear an oath of silence, propositions him with the prospect of having a sexual relationship with Phaidra. Hippolytus cruelly denounces Phaidra’s desire. Phaidra stands at the palace door and hears what Hippolytus shouts at the nurse. In response she decides that her case is lost and resolves to die, but not before plotting to guard her reputation. Before she exits into the palace herself, on her way to suicide, she swears the chorus of Troizenian women to an oath of silence, so that they do not repeat what they know.
Shortly after, the chorus, still outside the palace, hears shouting. Phaidra has hung herself, and her life expires before anybody can help. Just then, Theseus returns from visiting an oracle, wearing a crown of flowers that, ironically, indicates a favorable response. He grieves to find Phaidra suddenly dead, but cries out even more when he finds a wax tablet in Phaidra’s hand, containing a note written in her own handwriting, which accuses Hippolytus of raping her. In his anger, Theseus calls down one of the three fatal curses granted to him by his mythical father Poseidon on Hippolytus. When Hippolytus runs in to answer Theseus’ call, he tries to defend himself on the ground that such an act would be unthinkable to him, but Phaidra’s body and note have convinced Theseus too deeply. In case the death curse fails, he exiles Hippolytus from both Troizen and Athens.
A short while later, a messenger enters. He had gone along, the messenger explains, with a large group of friends, to escort Hippolytus to the border of the country to begin his exile. Just as Hippolytus mounted his chariot to depart along the shore, an earthquake rumbled, a massive wave appeared, and then from the wave a bull ran forth and chased Hippolytus. As an able charioteer, Hippolytus did his best to escape, but the bull caused the chariot to collide with a cliff and flip. Hippolytus himself was dragged along the ground, tangled in the reins. When his friends finally found him, he was on the verge of death. Hearing the story, Theseus feels somewhat hushed, but mostly satisfied that Hippolytus met with his punishment.
Suddenly, Artemis appears high above the stage. At once, she tells the whole truth to Theseus, who can hardly bear to hear how he believed the false accusation against Hippolytus, refused to wait for a fair trial, and called down the irreversible fatal curse. He blames an ancient unresolved crime among his ancestors for the suffering. At last Hippolytus, dying, is carried onto the stage by his friends and set down before Theseus. Both feel enormous pain and sadness for the other. Artemis ensures that they have a moment of reconciliation, forgiving each other, before she promises to take her own vengeance on Aphrodite and set up a cult in which young maidens will honor the memory of Hippolytus for all time.