In the X-Men universe, genetic mutations have become commonplace, giving superpowers to a growing share of the population. These superhuman qualities are generally revealed in adolescence, a critical moment during which a mutant can also sink into doubt and misguidance, and thus can as much succeed in misuse of his gifts as to become a full-blown individual.

In order to help them overcome this difficult time, Professor Charles Xavier created a specialized school where he trained them to use their powers and to accept themselves. It also teaches them to live in harmony with "normal" humans.

But other mutants, who have not had the chance to meet Professor Xavier, have gone astray on the path of evil. Clustered around the evil mutant Magneto, their only aim is to assert their pre-eminence by reducing humanity into slavery ...