Construction of the Great Smoky Mountains National Park is well underway in 1937 when the National Park Service recruits a young, freshly trained linguist, Thomas Haller, to investigate what life was like for residents before the park's creation. Also required to do a speech study of the stigmatized regional dialect, Haller conducts in-depth interviews with older residents, many of whom were born before the Civil War. John Stoll, an old man known in the mountains as a true believer in witchcraft, a witchdoctor, and "a good talker," regales Haller for hours with stories about an infamous witch, Mary Hess, who tormented her neighbors. She had the power to hex cows, cause sickness and crop failure, spoil milk, ride horses and people at night to exhaustion, move objects, and control the spirits of animals. Others said she could squeeze through a keyhole and shape-shift into a cat, crow, or dog. Haller dismisses witchcraft as pure nonsense, but Mary Hess intrigues him, and he decides to set aside his dialect work to learn more about her. Was she really a witch? Near the end of his investigation, Haller experiences a recurrent dream where a beautiful young woman beckons him to join her in eternity. He soon learns she is the Nesting Witch who haunts White Oak Flats in Sevier County. In his cabin, objects mysteriously move about and Haller feels under constant watch by an indefinable entity. Eventually, he is visited by the ghastly spirit of Mary Hess, which he rationalizes as a "change in sensibility," and his faith in science is challenged.