A traitor in the battle threatens the efforts of the X-Men and the Brotherhood against Magneto, who has another secret weapon -- the Sentinel robot.

At Xavier's urging, the Brotherhood and the X-Men unite to battle Magneto; and the Institute begins to self-destruct while students are trapped in the mansion.

Magneto steals plans for a top-secret project that produced super soldiers. Wolverine worked on it during World War II.

Mystique frees a mutant called the Scarlet Witch from an asylum, hoping she'll help the Brotherhood, but Mystique doesn't know the witch is seeking revenge on Quicksilver and Magneto.

Jean's telepathy changes, arriving in surges she can't control; and Hank McCoy joins the faculty as a science-and-gym teacher.

Xavier suspects that a flying "angel" seen above New York is a mutant, and he sends Cyclops and Rogue to find him before Magneto does.

Jean is possessed by a mutant with telepathic powers, which he uses to control the students and have them help him in his plot to release the imprisoned Apocalypse, a mutant who wishes to enslave the human race.

Forge invents a teleporter, and Nightcrawler uses it to travel large distances, but inadvertently opens a portal that allows strange creatures to follow him back to the school.

When Cyclops and Nightcrawler save people from a car crash they question Xavier's desire to keep their identities a secret. Meanwhile, the Brotherhood terrorize people in a crowded stadium.

The serum Hank McCoy uses to control his mutation no longer works, and his students are afraid of his angry outbursts.

The young X-Men are left alone in the mansion when the adults respond to a jailbreak, and they throw a party that doesn't end well.

Nightcrawler has a crush on a new student. The wild girl is grounded for breaking the rules, but things get worse when her father arrives and asks that she help him in a bank robbery.

Avalanche wants to join the Institute, but has trouble being accepted by the others, especially after he's accused of taking joyrides on the X-vehicles at night.

Beast is mistaken for Bigfoot by hunters while he's on a camping trip with the students.

The women form a team of crime fighters after Jean and Amara are teased for having weaker powers, and they call themselves the Bayville Sirens.

Havok is swept out to sea while surfing in Hawaii, and Scott saves him, but they both end up stranded and have to work together to survive.

The X-Men help Storm when her abilities are threatened by a visiting African witch doctor who attempts to steal her powers.