X-Men: First Class

In 1962, two young men on opposite ends of the same argument build a school and a war between them, against the background of the Cuban Missile Crisis.

It resets the series by going back rather than forward. Charles Xavier and Erik Lehnsherr meet as young men, recruit together, fight together, and separate over a disagreement neither of them ever wins, and the film puts all of it inside thirteen days of real history that the audience already knows the ending to.

The period setting does most of the work. A story about a hidden minority being recruited by governments who fear them lands harder in 1962 than it does in the present, and the film is confident enough to let the political thriller carry the superhero plot rather than the other way round.