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.
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.
In the 1960s, superpowered humans Charles Xavier and Erik Lensherr work together to find others like them, but Erik's vengeful pursuit of an ambitious mutant who ruined his life causes a schism to divide them.
The X-Men send Wolverine to the past in a desperate effort to change history and prevent an event that results in doom for both humans and mutants.
In the 1980s the X-Men must defeat an ancient all-powerful mutant, En Sabah Nur, who intends to thrive through bringing destruction to the world.
As Jean Grey's powers surge out of control, she transforms into the formidable Dark Phoenix, forcing the X-Men to confront the devastating question: is her life worth the cost of humanity's survival?