Semele, the daughter of King Cadmus, is due to marry Prince Athamas, though secretly she loves Jupiter, father of the gods. Her sister Ino is unhappily in love with Athamas and can barely conceal her despair – much to her father’s displeasure. Athamas is shocked when he realizes that he’s the reason for Ino’s sorrows. A bewildered Cadmus announces that Jupiter, in the guise of an eagle, has carried off Semele.
Semele enjoys the pleasures of love. Jupiter’s wife Juno hears about her husband’s new lover from her messenger Iris. She is consumed with jealousy. Semele loves Jupiter beyond all measure but is painfully aware of an insurmountable barrier between herself and the god. Jupiter is troubled by this and does all he can to distract Semele.
– Interval –
Aided by Somnus, the god of sleep, Juno appears to Semele as her sister Ino, whispering that she can become immortal if she sees Jupiter just once in his true, divine form. At their next rendezvous, Semele demands maximum fulfilment. Jupiter is unable to dissuade the woman he loves so much and she is burnt to death in the supreme deity’s fiery rays. Jupiter proclaims through Apollo that Dionysus, god of ecstasy, shall rise from her ashes. Ino and Athamas become the new royal couple and their wedding is joyously celebrated.