The human government develops a cure for mutations, and Jean Gray becomes a darker uncontrollable persona called the Phoenix who allies with Magneto, causing escalation into an all-out battle for the X-Men.

After a car crash, a criminal psychiatrist awakens to find that she's a patient in the same mental institution that currently employs her.

When anti-mutant Colonel William Stryker kidnaps Professor X and attacks his school, the X-Men must ally with their archenemy Magneto to stop him.

In a world where mutants (evolved super-powered humans) exist and are discriminated against, two groups form for an inevitable clash: the supremacist Brotherhood, and the pacifist X-Men.