Everything seems normal in Winslow, Washington, as the tourists arrive for summer fun—the carnival in Prospect Park, the ghost-town tour—and the locals retreat to Ruby Creek to cool off. The only thing that's unusual is the death of Pard Holloway's cattle after a brief, strange illness.

But now the disease seems to be spreading to humans. One by one, individuals deteriorate into lunacy. Seventeen-year-old Hazel Winslow, however, is perfectly healthy. That leaves her to confront the crisis on her own while her father, the sheriff, heads into the woods to hunt a fearsome creature; her boyfriend grows delusional; and ghosts invade her grandmother's broken-down mansion. How can she reason with them when their minds aren't functioning? And what would be worse—succumbing to the sickness, or being the last sane person left?

Inspired by true events and informed by historical accounts, this modern Gothic tale evokes the mass hysteria of the Salem witch trials and the terror of the events in Pont-Saint-Esprit, France, in 1951.

Contains mature themes.