The X-Men's newest crisis is shaping up to be their final adventure! It all starts with a mysterious and tragic disappearance, but the X-Men's investigation draws the team into a much larger - and deadlier - situation! Who or what are the Four Horsemen of Salvation - and what is their connection to Nate Grey, the incredibly powerful mutant known as X-Man? Will Nate's home dimension, the Age of Apocalypse, make its horrifying return? Or does the dawn of the Age of X-Man mean the end of the Uncanny X-Men?! It's a status-quo-smashing story that just might leave all of mutant-kind in tatters - and it will take three fan-favorite writers to deliver the mutant madness!