Well-respected Pompeiian Glaucus performs an act of kindness by purchasing Nydia, a blind slave being mistreated by her owner. Nydia falls in love with her new master, but he only has eyes for Ione. Ione in turn is lusted after by Arbace, an Egyptian high priest of Isis. When Nydia beseeches Isis for help in capturing Glaucus' heart, Arbace gives her a "love" potion-- an elixir made to drive Glaucus mad, securing Ione for himself. Ultimately, Mount Vesuvius will end their lives and seal their fates in a terrible, glorious eruption.