Montana Territory, 1878. Wolf Creek is under siege by a vicious, flesh-eating evil that stalks the night, leaving dismembered and devoured corpses in its wake. It is unknown, unseen, and unstoppable. Enter Joseph Longtree, deputy U.S. Marshal. He knows there is a rhyme and reason behind the killings, but to discover the truth will mean penetrating local superstition, corruption, and vice, which will ultimately bring him face to face with a monstrosity out of Native American folklore.