Rachel Summers claims the power of Phoenix, Jean Grey returns from a watery grave and the original X-Men reunite as X-Factor! It's an era of upheaval that puts Marvel's mutants on the path to some of their darkest days! Both Cyclops and Professor X leave the X-Men, but a new teammate waits in the wings: Magneto?! As Storm steps up and Wolverine faces the new Phoenix, the relentless Nimrod targets the team for annihilation! Meanwhile, the newly minted X-Factor grapples with Jean's miraculous resurrection and shares a fateful first encounter with Apocalypse!