In a dystopian future, mutants and their human allies are on the brink of extinction, hunted by formidable robots known as Sentinels. These machines are able to adapt and counteract mutant powers, making them nearly impossible to defeat. The bleak world is the result of a historical assassination, which inflamed mankind's fear and hatred towards mutants, accelerating the Sentinel program. In a desperate bid to prevent this dark future, the remaining X-Men hatch a plan to alter the past. They decide to send Wolverine's consciousness back in time to his younger body in the 1970s. His mission is to unite a fragmented and disillusioned group of mutants to avert the pivotal event that sets off the chain reaction leading to the dystopia.

Upon arriving in the past, Wolverine seeks out the younger versions of Professor X and Magneto, who are estranged and dealing with personal demons. Convincing them of the grim future, Wolverine works to bring them and other key mutants together. They must overcome their deep-seated conflicts, personal rivalries, and vastly different ideologies to change the course of history. This task is made more complicated by the Sentinels' origins, governmental distrust of mutants, and the shaping forces of history that resist change. The tenuous group must navigate these hurdles while confronting their own internal battles and the realization of what their futures may hold.