The Dunwich Horror is a short story by H. P. Lovecraft. It takes place in Dunwich, a fictional town in Massachusetts and is considered one of the core stories of the Cthulhu Mythos.
In the isolated, desolate and decrepit village of Dunwich, Wilbur Whateley is the hideous son of Lavinia Whateley, a deformed and unstable albino mother, and an unknown father (alluded to in passing by mad Old Whateley, as "Yog-Sothoth"), and strange events surround his birth and precocious development. Wilbur matures at an abnormal rate, reaching manhood within a decade, locals shun him and his family, and animals fear and despise him (due to a smell he gives off). All the while, his sorcerer grandfather indoctrinates him into certain dark rituals and the study of witchcraft.
Wilbur wants to acquire an unabridged Latin version of the Necronomicon so that he may open the way for the return of the mysterious "Old Ones", whose forerunner is the Outer God Yog-Sothoth. Thus, Wilbur and his grandfather have sequestered an unseen presence at their farmhouse; this being is connected somehow to Yog-Sothoth. Year by year, this unseen entity grows to monstrous proportions, requiring the two men to make frequent modifications to their residence. People begin to notice a trend of cattle mysteriously disappearing. Wilbur's grandfather dies. His mother disappears soon afterward. The colossal entity eventually occupies the whole interior of the farmhouse.