In one of the hottest summers for decades, New York City is being swept by a strange and terrible epidemic. Doctors are helpless as victims fall prey to a bizarre blood disorder. They can no longer eat solid food, they become hypersensitive to sunlight - and they have an irresistible need to drink human blood. As panic grips the city, and mobs of bloodthirsty people roam the streets, self-taught psychic Harry Erskine has to enter the shadowy realms between the living and the dead, and call on America's native spirits to help him in a struggle for human survival in which death is only the beginning...