For acting Lieutenant Jim Chee, the murder of a Navajo Tribal Police officer seems like an open-and-shut case when he discovers a Hopi poacher huddled over the victim's butchered corpse. However, Chee's newly retired predecessor, Joe Leaphorn, believes otherwise.

Hired to find a missing biologist who was searching for the key to a virulent hidden plague—and who vanished in the same area and on the same day the policeman was slain—Leaphorn suspects both events are somehow connected. And the reported sighting of a "skinwalker"—a Navajo witch—has Leaphorn and Chee seeking answers to a deadly riddle in a dark place where superstition and science collide.