Chayatocha by Shane Johnson

One hundred forty years ago, pioneers traveling to the American West faced a rugged and dangerous journey. But when Daniel Paradine, his family, and a small band of fellow travelers guide their wagons into a treacherous mountain detour, no one is prepared for the evil that awaits them. Finding themselves in a land of inexplicable cold and darkness, the travelers begin disappearing one by one. In a desperate search for his missing family, Paradine comes face-to-face with the beast responsible for the terror--an ancient creature, beyond human, that allows him to live only to accomplish its most sinister desire.