Undead Nightmare introduces hours of a new single-player storyline and brand new multiplayer content. Seemingly overnight, a zombie plague ravages the once bountiful frontier, decimating the landscape and reawakening the dead. In towns, settlements and outposts throughout the world, the uninfected citizens are left to fight for survival against waves of the undead. John Marston must ride out into the vast and terrifying world and survive long enough to find a cure.