Magneto builds a home strictly for mutants on the orbiting base known as Asteroid M. The message goes out worldwide of initial exodus, and he finds just as many eager to join him, as those anxious to destroy him.

With Magneto seemingly dead, Fabian Cortez takes over Asteroid M, and initiates a nuclear war with Earth. The X-Men attempt to sabotage his warhead stockpile, and rescue Gambit, finding assistance in the most unlikely of places.

Snatched from the jaws of the Phalanx by the villainous Mr. Sinister, Beast and Forge search for allies to help them battle the alien threat. Gathering assistance from such unlikely sources as Magneto and Sinister himself, they embark upon a daring and risky plan to free the planet from the clutches of the Phalanx by traveling straight into the belly of the beast.