ACROSS THE VAST WESTERN FRONTIER, A PLAGUE IS SPREADING. When former outlaw John Marston wakes up at his farmhouse, he finds a world gone insane: overnight, deranged hordes have overrun the towns and outposts of the American frontier. In a desperate attempt to save his family, Marston must traverse a world torn apart by chaos and disorder, using every skill he has to survive long enough to find a cure.