Artemis Blythe has returned to her old stomping grounds, this time as an official consultant of the FBI. And this new case will be like none other. A mass grave is found in the mountains. The bones of long forgotten victims hidden in a mineshaft. The mountains outside Pinelake are combed for more victims. And then another mass grave is found. And another. And while Artemis sets out with Agents Grant, Forester and Wade to solve the old cases, she's faced with a spine-chilling thought. What if some of these bones belong to her sister? Helen disappeared around the same time as these graves were formed. In a twist, Artemis is forced to confront old fears in a race against the clock to find the most prolific serial killer she's ever heard of. And through it all... she can only hope her sister Helen isn't identified among the slain.