The play focuses on the struggle between erotic love, represented by the goddess Aphrodite and the character of Phaedra, and the virtue of sophrosyne represented by the goddess Artemis and the character of Hippolytus. It's setting is the household of the exiled Greek king Theseus in the Peloponnesian city of Troezen.
Theseus's wife Phaedra conceives a violent passion for her step-son Hippolytus, and kills herself when it is not returned. However, she leaves behind a letter accusing Hippolytus of rape. Theseus sends his son into exile. As Hippolytus departs, his chariot is attacked by a bull from the sea. As he lies dying, the goddess Artemis appears to tell Theseus the truth, and father and son are reconciled before Hippolytus's death.
Free online texts
Bartleby: Hippolytus, translated by Gilbert Murray, Harvard Classics (1909-14) edition. HTML format.
Gutenberg: Hippolytus; The Bacchae, translated by Gilbert Murray. Multiple formats.
Gutenberg: The Tragedies of Euripides, Vol I, translated by Theodore Alois Buckley (1892). Multiple formats.
Internet Archive: Hippolytus, translated by Gilbert Murray (1904). Multiple formats.
Internet Archive: Hippolytus, Greek text with notes by R.A. Paley (1876). Multiple formats.
Internet Archive: Hippolytus, Greek text with notes by F.A.S. Freeland. Multiple formats.
Internet Classics Archive: Hippolytus, translated by E.P. Coleridge. HTML and TXT formats.
Loebulus: L012 - Euripides -- Euripides IV: Ion. Hippolytus. Medea. Alcestis. Greek and English parallel text. Loeb edition, PDF format. Also available from the Internet Archive.
Poetry in Translation: Hippolytus, translated by George Theodoridis (2010). Multiple formats.
University of Adelaide (Internet Archive): Hippolytus, translated by E.P. Coleridge. Multiple formats.
Gutenberg: Euripides and His Age, by Gilbert Murray.
History of Ancient Greece: Early Euripides, podcast by Ryan Stitt.
Librivox: Hippolytus. Public domain audiobook.
Theatre History: Hippolytus, summary and analysis.
Wikipedia: Hippolytus (play)
The Great Conversation: Further reading at Tom's Learning Notes
Seneca: Phaedra or Hippolytus - Latin adaptation.
A.E. Haigh: The Tragic Drama of the Greeks (1896).
Ancient Greek resources: Learn to read Greek classics in the original.
Bloom's Western Canon: Hippolytus is listed.