In a house under renovation, a plumber uncovers a hidden cellar and makes a grisly discovery: a decapitated chicken, animal bones, and cauldrons containing beads, feathers, and other relics of religious ceremonies. In the center of the shrine rests the skull of a teenage girl. Meanwhile, on a nearby lakeshore, the headless body of a teenage boy is found by a man walking his dog.

Forensic anthropologist Temperance Brennan is called in to investigate, and a complex and gripping tale unfolds. Nothing is clear--neither when the deaths occurred, nor where. Was the skull brought to the cellar or was the girl murdered there? Why is the boy's body remarkably well preserved? Led by a preacher turned politician, citizen vigilantes blame devil worshippers and Wiccans--and Temperance will need all of her expertise to get to the real culprit first.