In the dark recesses of the Galaxy waits an alien race. More machine than organic, they seek out inferior races which they can assimilate. They are called the Phalanx, and they have just targeted Earth as their next meal.
Humanity is helpless against the onslaught of the assimilation the Phalanx brings. Those creatures that are genetically different, known to us as mutants, possess the ability to defend themselves against the Phalanx. Of those, the group known as the X-Men present the greatest threat to the Phalanx's plans for domination.

Through means of assimilation, subterfuge, and incursion, the Phalanx have prepared a preemptive strike against the X-Men. Armed with this knowledge, the mutants have launched a desperate strike of their own, to find seven fledgling mutants: Husk, Chamber, Skin, Jubilee, M, Synch and Blink -- all that stand between the Phalanx and victory.