American Delapore restores his ancestral Exham Priory and begins hearing innumerable rats racing within the walls at night. He leads a party into a vast sub-cellar, where millennia of his family's atavistic rites are laid bare in stone and bone.
Lovecraft's most forceful treatment of hereditary degeneracy, it suggests civilisation is only a thin veneer over primordial savagery. Its narrator's descent — physical and psychological — is among the most structurally elegant in his work.