Charles Xavier is dead. Cyclops and Wolverine each lead their own team of X-Men. Mutantkind is divided like never before. In a desperate bid to save Xavier's dream, the Beast brought the original X-Men forward to the present. Now, with the timeline -- and all of existence -- in jeopardy from their presence, they must go back. But faced with the horror of what fate would have in store for them, young Jean Grey and Scott Summers are intent on staying and forging their own destiny. And as debate rages and tempers flare, the X-Men of the future arrive with a dire warning, seeking to prevent history's greatest mistake.