The CLIMACTIC SHOWDOWN between the X-MEN and the new BROTHERHOOD OF EVIL MUTANTS! Who will be left standing after the world's mightiest mutants throw down? And when the dust settles, not everything is as it seems.

In this second volume in the Ultimate Series, the X-Men are captured and forced into service for the government's nefarious Weapon X program. Will they be rescued by Wolverine, or will they be forced to commit terrible acts as government agents?

It's the climactic story this series has been building to, guest-starring the allies Legion has made along the way...and not all of them will emerge unscathed! One of Legion's most troublesome personalities threatens to annihilate an alien species, and S.W.O.R.D. director Abigail Brand is on the case - but will she be able to work with David to solve this extraterrestrial conundrum? Legion prepares for a final showdown with the monster in his mind...

The ultimate X-Men ensemble fights a war for the survival of the species across two time periods. The characters from the original X-Men film trilogy join forces with their younger selves from X-Men: First Class in an epic battle that must change the past --and save our future.

Before Charles Xavier and Erik Lensherr took the names Professor X and Magneto, they were two young men discovering their superhuman powers for the first time, working together in a desperate attempt to stop the Hellfire Club and a global nuclear war.