On a rugged Colorado mountain ridge, Mattie Cobb and her police dog partner Robo make a grisly discovery―and become the targets of a ruthless killer.

Colorado’s Redstone Ridge is a place of extraordinary beauty, but this rugged mountain wilderness harbors a horrifying secret. When a charred body is discovered in a shallow grave on the ridge, officer Mattie Cobb and her K-9 partner Robo are called in to spearhead the investigation. But this is no ordinary crime―and it soon becomes clear that Mattie has a close personal connection to the dead man.

Joined by local veterinarian Cole Walker, the pair scours the mountaintop for evidence and makes another gruesome discovery: the skeletonized remains of two adults and a child. And then, the unthinkable happens. Could Mattie become the next victim in the murderer’s deadly game?

A deranged killer torments Mattie with a litany of dark secrets that call into question her very identity. As a towering blaze races across the ridge, Cole and Robo search desperately for her―but time is running out.