The Witch of Vesuvius, though she has no supernatural powers, shows Bulwer-Lytton's interest in the occult—a theme which would emerge in his later writing, particularly The Coming Race.

A popular sculpture by American sculptor Randolph Rogers, Nydia, the Blind Flower Girl of Pompeii (1856), was based on a character from the book.

Athenian nobleman Glaucus arrives in the bustling and gaudy Roman town and quickly falls in love with the beautiful Greek Ione.

Arbaces, recovered from his wounds, overhears and stabs Apaecides to death; he then pins the crime on Glaucus, who has stumbled onto the scene.

Nydia leads Glaucus and Ione to safety on a ship in the Bay of Naples, as because of her blindness she is used to going about in utter darkness while sighted people are made helpless in the cloud of volcanic dust.

The next morning she commits suicide by quietly slipping into the sea; death is preferable to the agony of her unrequited love for Glaucus.