What happens when the skeletons in your closet finally break down the door and come looking for you? The X-Men are about to find out! In the wake of the tragic events of the House of M, the mutant community is in turmoil, and the X-Men are bearing the brunt of this new world order. Amid the chaos, a new enemy awakens, one whose very existence will haunt the founding members of the X-Men like nothing has before. Who is this new threat? How is he tied to Professor X´s darkest secret? Cyclops, Wolverine and the rest of the team must find out soon, before they and those closest to them go mad! Fan-favorite creators Ed Brubaker and Trevor Hairsine present a mysterious blend of horror and super-heroics that changes everything for the X-Men!