The play takes place at Troezen, at the house of the Athenian king Theseus. In the first scene, Theseus’s son Hippolytus discusses his father’s six-month absence with his tutor, Theramenes, and his plans to leave in search of him. He is ashamed that he has not acted sooner and that he has not yet proved himself by fighting any monsters. Theramenes challenges Hippolytus’s decision, suggesting that he is fleeing from something else: His love for Aricia, the last surviving member of the house of Theseus’s uncle Pallas. Theseus killed Pallas and his sons years earlier when they tried to seize the throne. Aricia was left alive, but forced to remain celibate. Hippolytus admits his feelings for Aricia and hopes that leaving Troezen will cure him of them, especially as he has always committed to maintaining his sexual abstinence. Before leaving, Hippolytus intends to see his stepmother, Phaedra, with whom he has always had a fraught relationship.

As Hippolytus and Theramenes are speaking, Phaedra’s nurse Oenone enters, initiating the brief second scene. She explains that her “mistress” has been suffering from a mysterious illness, but that she has just now arisen from bed to look at the daylight.