From the introduction:
The world of Marvel is a fantastical one to be sure. There’s a marvel to be seen on every street corner, on every rooftop and in every park. Overhead, superheroes zoom around. Fighting villains, stopping the end of the world every day, even fighting each other. Especially fighting each other. Heroes fight each other more than they do villains right now.
In fact, that’s pretty relevant to what you’re going to be doing. You’re in Earth-616 right now and the year is 2012. It’s not been too long since Scarlet Witch said No More Mutants and the Mutant race was almost wiped out. Cyclops and his two hundred or so mutants don’t have much hope left, outside one little source. Hope Summers, the Mutant Messiah, who may hold the key to restoring mutantkind. A key whose lock has just arrived.