As he finishes a cup of his morning coffee, retired cop and former detective Pat Donegal gets a curious call from the Kickapoo County Chief Deputy Hennie Duggan. A gruesome discovery of human remains on a ridge portends grisly possibilities that neither man wants to consider. Donegal, physically and emotionally hungover from a rough break-up, is known for his unorthodox methods and a tendency to bend the rules. Even though Duggan chafes at his style, he knows he needs a skilled investigator like Donegal to have his back.

As strange details continue to emerge, the detectives enlist the help of city cop and data expert Shea Sommers. As the team crisscrosses the state to chase a few promising leads, their search expands beyond local guides and neighbors to members of a sinister, secret hunting society. When Duggan mysteriously disappears—and becomes a suspect himself—Donegal must take over the investigation. He soon realizes the case might not only be unsolvable but could land him in prison—or an early grave.