Cadmus, son of King Agenor and brother of Europa, was instructed by the goddess Athene to sow the teeth of a dragon he had slain. Out of the ground sprang armed men, who helped Cadmus found the city of Thebes. Cadmus married his youngest daughter, Agave, to one of these men, Echion. His second daughter, Semele, was consumed by love for Zeus. The supreme god’s consort Hera, taking on the appearance of Semele’s nurse Beroë, persuaded her to demand that her lover Zeus show himself to her in his divine form. The blazing splendour of the father of the gods burned Semele to ashes. Zeus however saved her unborn child, Dionysus, and sewed him up in his thigh – out of which Dionysus was born a second time. Semele’s tomb in Thebes became a shrine.
Pentheus, son of Echion and Agave, has succeeded his grandfather Cadmus to the throne of Thebes. As the people await their new ruler, the voice of a stranger announces from afar that Dionysus has come to Mount Cytheron. The masses follow the call and join Dionysus’s retinue, the Bassarids, who worship the god in ecstatic,
intoxicated rituals. While Cadmus warns that one should not get on the wrong side of the new god, his daughters Agave and Autonoë cast doubt on Dionysus’s divinity. The hermaphroditic seer Tiresias on the other hand is keen to take part in the orgiastic rituals. Pentheus proclaims an absolute ban on all worship of the alleged god Dionysus and his mother Semele. Agave, Autonoë and Tiresias however fall under the stranger’s spell when they hear him calling again, and set off for Mount Cytheron. Pentheus dismisses his grandfather Cadmus’s repeated warnings and gives orders for all devotees of Dionysus to be locked up. The captain of the royal guard brings the captives from Cytheron, among them Agave, Autonoë, Tiresias and the stranger. Pentheus attempts to question his mother Agave, who is in a trance, about the goings-on on Mount Cytheron, but gets nothing out of her. Beroë, Pentheus’s nurse, tries without success to warn the young king about the stranger, whom she has recognized as the god Dionysus. Pentheus interrogates the stranger, who is unmoved by his threats and outbursts of violence. The king orders the stranger to be incarcerated and tortured. But the next moment the stranger once again stands unharmed before Pentheus, who increasingly succumbs to his seductive words.
Tiresias, Agave, Autonoë and the captain of the royal guard perform a play, »The Judgement of Calliope«. It tells of the siring and unconventional »birth« of Adonis (captain) – a handsome youth claimed by both the goddess of love Venus (Agave) and the queen of the underworld, Proserpina (Autonoë). Calliope (Tiresias), the muse of epic poetry, is to adjudicate in the dispute between the two goddesses. She makes an equitable judgement, awarding each goddess the coveted youth for one third of the year, with Adonis having the remaining third to himself. At the end Adonis reports that he was gored to death by Venus’s jealous lover, the war god Mars, who had taken the shape of a wild boar. The piece ends with an lament by all the players.
Increasingly under Dionysus’s spell, Pentheus is determined to see for himself what is happening on Mount Cytheron, and goes there disguised as a woman. Dionysus rouses his followers against Pentheus. The frenzied mass of Bassarids, including Agave and Autonoë, kill the intruder. Full of foreboding, Cadmus and Beroë await the return of the Bassarids. They enter triumphantly, led by Agave, who proudly presents her bloody trophy. Cadmus confronts his daughter with the reality: she gradually comes to realize that what she is holding is not a young lion’s head but the mortal remains of her own son. The stranger reveals himself to all as the god Dionysus. He banishes the royal family from the city and commands that the palace should be burnt down. He calls on Persephone (Proserpina) to free his mother Semele from the clutches of Hades so that she can take her place among the immortals as the goddess Thyone.