"Age of X" is a comic book storyline published by Marvel Comics as part of its X-Men series. The storyline is set in an alternate reality known as Earth-11326. Running from January to April 2011, it is similar in name and tone to the 1995 "Age of Apocalypse" storyline.
Plot
Background
After the announcement of the storyline in December 2010, Marvel added QR codes on selected comics. These codes were linked to five different historical logs, each providing background for the "Age of X". Log 1A: "Anti-mutant protestors beat mutant-rights advocate Henry McCoy to death during the March For Purity in Washington, D.C." Log 2B: "The mutant abilities of a young mutant named Jean Grey manifested in the form of an explosive, fiery phoenix that immolates everything in its path. The city of Albany, New York, is decimated, leaving 600,000 dead." Log 3C: After the Phoenix demolished Albany, New York, the U.S. government sponsors the mass production of Exonim Sentinels: technologically advanced combat vehicles designed to subdue mutants. In the months that follow, the mutant population drastically declines; this period becomes known as "the Decimation". The log shows a dead Scarlet Witch, while Quicksilver fights an Exonim. Log4D: "As anti-mutants hysteria spreads, legislation is passed that requires all mutants to be imprisoned and, in most cases, executed. When a fugitive mutant that Reed Richards has allowed shelter in the Baxter Building (despite wife Sue Storm's protests) accidentally injures her son Franklin, Sue reports Richards to the authorities. To demonstrate that no one is above the law, the Fantastic Four is publicly arrested and marched out of the Baxter Building in handcuffs." The log shows that the harbored mutant is Wolfsbane. Log5E: "In the aftermath of the decimation, only a fraction of the worldwide mutant population remains at large. These fugitive mutants are believed to be the most powerful... and the most dangerous. To track down and eliminate these threats, the United States assembles a group of human superheroes. They are called The Avengers." The log shows team members Captain America, Iron Man, Hulk, Ghost Rider, the Invisible Woman (Sue Storm) and Redback (Jessica Drew).
Main story
The mutants are almost extinct, tortured by a strike force led by Colonel Graydon Creed. The first signs of the Age of X appeared in X-Men: Legacy #244; the events were removed from the Earth-616 mainstream continuity, with no memories of the alternate lives.
The primary event occurs 1,000 days after Magneto moved most of the mutants to Fortress X, their last bastion. Human forces are trying to reach the citadel; although they have always failed to do so, they have inflicted many casualties on the mutants. Legacy/Rogue acts as a "Reaper", storing the thoughts of those killed in battle. After one of her reapings, Legacy sees the capture of Shadowcat (who was returning from a mission in the outside world). Rogue finds the camera which Shadowcat is trying to hide, and discovers that all the pictures in it are blank. Using Madison Jeffries's absorbed powers, Legacy infiltrates the X-Brig (Fortress X's detention facility) to question Shadowcat. There she is seen by the Earth-616 Blindfold, who hints that this reality is "wrong" and asks her to ask Professor X about the "scar tissue". As she speaks with Shadowcat and touches a comatose Xavier, Legacy begins a mental attack on every mutant inside the fortress; seen by Danger, she becomes a fugitive. Hunted by Dani Moonstar's Cadre, she is saved by Gambit. They are attacked by Magneto, who fakes their deaths and explains that he sent Shadowcat out to investigate because he is convinced something is wrong. As Magneto returns to the brig to free Shadowcat and Professor X, X (the voice controlling Fortress X) sends the Cadre after him. Gambit and Legacy (who are in the room at the center of the fortress) discover that their universe has been stolen and is kept in a box. When Professor X is freed, he telepathically shows his pursuers and a reluctant Legion the truth about himself and the reality in which they think they are living. The Age of X was created when Legion's mind reacted to Doctor Nemesis's attempt to restore it to sanity. A new persona (with new powers) was born, creating a new reality to protect Legion's personalities. This manifestation of Legion's power assumed the appearance of Moira MacTaggert to confuse Xavier and protect Legion. Moira confronted Legacy and Gambit, revealing that she is also X. Cornered by Xavier, X launches a last offensive on the fortress.