Well respected Pompeiian Glaucus performs an act of kindness by buying Nidia, a blind slave being mistreated by her owner. Nidia falls in love with her new master, but he only has eyes for Jone. Jone in turn is lusted after by Arbace, an Egyptian high priest of Isis. When Nidia beseeches Isis for help in capturing Glaucus' heart, Arbace gives her a "love" potion, which really will affect his mind and not his heart, thus opening the way to Jone for himself. When Arbace's disciple is murdered Glaucus finds himself in hot water, shortly after which Mt. Vesuvius erupts.