When 13-year-old Heather Church vanishes from her Colorado home, the only clue is an unlocked window and a chilling sense that something far more sinister has occurred. Two years later, her skull is discovered in a remote area — a breakthrough that places investigators on the trail of one of the most prolific serial killers in U.S. history. As the truth unfolds, detectives realize Heather’s case is just one piece of a monstrous pattern of violence.