In the haunting aftermath of the Civil War, principled Yankee Lawman Beau Riffen joins forces with Cody Parnum, a tormented ex-Confederate tracker. Their quest to apprehend notorious train robbers leads them to Purgatory, a town eerily deserted. Amidst the silence, they cross paths with a lone African American trapper and a prisoner harboring secrets who whispers of an ancient menace. As the shadows of Purgatory tighten, an impending confrontation with "Yee Naaldlooshii" - The Skinwalker - beckons, testing bonds of trust and humanity in their gripping fight for survival.