The narrative centers on an antiquated colonial house in Benefit Street, Providence, which has harbored an abnormally high mortality rate since its construction in seventeen sixty-three. Successive occupants and servants either succumbed to a wasting anemia, descended into madness, or uttered incoherent ravings in French while exhibiting aggressive, vampiric tendencies. The narrator's antiquarian uncle, Doctor Elihu Whipple, compiles extensive historical data on these tragedies, noting that the site originally served as a secret burial ground for French Huguenot refugees known as the Roulets.
Driven by a profound curiosity, the narrator investigates the property's deeds and uncovers a lineage of the demonic, linking the current manifestations to Etienne and Paul Roulet, seventeenth-century outcasts associated with witchcraft and lycanthropy. Convinced that an anomalous, parasitic entity of immense malice survives in the damp, fungus-ridden cellar, the narrator and his uncle resolve to conduct an overnight vigil equipped with specialized scientific apparatus and destructive weaponry.
During their second night in the cellar, the uncle is overcome by a terrifying vision and dissolves into a gelatinous mass reflecting the shifting facial features of the cursed Harris family. Stricken with horror, the narrator flees but returns the following day determined to eradicate the abomination. Utilizing carboys of concentrated sulfuric acid, he floods the pit beneath the fireplace, successfully destroying the amorphous parasite.
In the aftermath, the house loses its malignant atmosphere, the unnatural vegetation withers away, and normal plant and animal life finally return to the grounds. The narrative concludes with a reflection on the permanence of memory and the relief of purging one of earth's nethermost terrors from a quiet residential street.
