Pompeii, A.D. 79. Athenian nobleman Glaucus arrives in the bustling and gaudy Roman town and quickly falls in love with the beautiful Greek Ione. Ione's former guardian, the malevolent Egyptian sorcerer Arbaces, has designs on Ione and sets out to destroy their budding happiness. Arbaces has already ruined Ione's sensitive brother Apaecides by luring him to join the vice-ridden priesthood of Isis. The blind slave Nydia is rescued from her abusive owners, Burbo and Stratonice, by Glaucus, for whom she secretly pines. Arbaces horrifies Ione by declaring his love for her, and flying into a rage when she refuses him. Glaucus and Apaecides rescue her from his grip, but Arbaces is struck down by an earthquake, a sign of Vesuvius' coming eruption.