Robin Cook's Acceptable Risk | 2001
A young woman, Kim Welles, inherits a 300-year-old house near Salem, Massachusetts, a house that once belonged to an ancestor, a woman hanged for witchcraft. While her husband, ambitious biochemist Edward Welles, is remodeling the house, he finds a mold growing in the dirt that could be the cure to a number of brain disorders and diseases, including Alzheimer's disease. As he skirts the rules and tests the mold on himself, his friend Bobby and other members of his research team, they come to realize that its potential benefits are countered by horrifying side effects, dangerous personality changes similar to those that eventually led Kim's ancestor to the gallows. When he begins hallucinating and people begin to die under strange circumstances, he discovers that his experiences are connected with the residents of Salem three centuries earlier and that the mold unleaches a demonic terror inside humans.