The setting of The Bacchae is the royal palace of Thebes, where Pentheus has succeeded his grandfather, Cadmus, as king. The play begins with a prologue spoken by Dionysus, the great god of wine and revelry himself. He announces that he has successfully spread his cult throughout Asia and returns now to the land of his mother, Semele, in order to teach the Greeks how to worship him through dancing, feasting, and sacrifices.

Some of the women of the city, including his own mother's sisters, have denied his status as a god, claiming he is simply a mortal and that the great Zeus killed his mother for lying about her lover. In threatening tones he describes how he has already driven the women of Thebes mad and sent them to the hills around the city, where they wear the animal skins of bacchants, priestesses of Dionysus...