When high-schooler Todd Tolanski starts exhibiting toad-like mutant powers, Mystique sees a perfect opportunity to get a spy into Xavier's institute. Meanwhile the X-Men recruit a new member as Kurt Wagner joins Xavier's school.
When Kitty Pryde discovers her mutant ability to phase through objects, Xavier sends Jean Grey on a mission to recruit her. Meanwhile, Wolverine's arch-nemesis, Sabretooth rolls into town and he's looking for a fight.
In Mississipi, a girl known only as Rogue learns she has power to absorb the memories, energy and powers of others. This frightens her, but also leads to both the X-men and the Brotherhood trying to find her for their own purposes.
A large mutant boy, Fred 'Blob' Dukes, enrolls in Bayville High. It is soon apparent that Fred has many issues deal with including his powers and his feelings about Jean.
Kurt becomes trapped in an alternative universe created by another young mutant known as Forge, who himself has been stuck there for more than 20 years.
Scott Summers and Jean Grey prepare for their geology club excursion, but Mystique has different plans in mind, replacing Jean with Rogue in an attempt to put further distance between her and the X-Men.
Spyke receives a video camera for a class assignment, but the camera is found by Wolverine's nemesis, Sabretooth, who uses it to find out where the Xavier Institute is in order to hunt down his rival, Wolverine.
While the X-Men and Brotherhood are at a survival training camp, Mystique releases the unstoppable Juggernaut. But when the unstoppable mutant threatens both teams, the X-Men and Brotherhood must work together in order to stop him.
Wolverine's tortured origin comes back to haunt him. In the Canadian wilderness, he runs into not only his arch rival Sabretooth, but also the doctor who gave him his Adamantium skeleton who still has insidious plans for him.
Scott finds out his younger brother Alex Summers, who he believed dead, is alive and maybe soon recruited by Magneto to join him as the X-Men are forced to fight the Brotherhood for a place in Magneto's sanctuary.
Magneto holds multiple battles to find out which mutants are "worthy" of joining him on Asteroid M. Where Magneto offers to greatly strengthen and increase the mutant abilities of the winners to their full and maximum potential.