In Ilmarsh, England, local police detective Alec Nichols discovers sixteen horses' heads on a farm, each buried with a single eye facing the low winter sun. After forensic veterinarian Cooper Allen travels to the scene, a pathogen is discovered lurking within the soil, and many of those who have come into contact with the corpses grow critically ill. A series of crimes comes to light-disappearances, arson, and mutilations-and in the dark days that follow, the town slips into panic and paranoia. Everything is not as it seems. Anyone could be a suspect. And as Cooper finds herself unable to leave town, Alec is stalked by an unseen threat. The two investigators race to uncover the truth behind these frightened and insidious mysteries-no matter the cost.