Since the dawn of civilization, he was worshipped as a god. Apocalypse, the first and most powerful mutant from Marvel’s X-Men universe, amassed the powers of many other mutants, becoming immortal and invincible. Upon awakening after thousands of years, he is disillusioned with the world as he finds it and recruits a team of powerful mutants, including a disheartened Magneto, to cleanse mankind and create a new world order, over which he will reign. As the fate of the Earth hangs in the balance, Raven with the help of Professor X must lead a team of young X-Men to stop their greatest nemesis and save mankind from complete destruction.

"Days of Future Past" is a popular storyline in the Marvel Comics comic book The Uncanny X-Men issues #141 and #142, published in 1981. It deals with a dystopian alternative future in which mutants are incarcerated in internment camps. An older Kitty Pryde transfers her mind into the younger, present-day Kitty Pryde, who brings the X-Men to prevent a fatal moment in history which triggers anti-mutant hysteria.

Before Charles Xavier and Erik Lensherr took the names Professor X and Magneto, they were two young men discovering their powers for the first time. Before they were arch-enemies, they were closest of friends, working together with other mutants (some familiar, some new), to stop the greatest threat the world has ever known.