Age of X; chapter 3

This is the third installment in this story. So far we know that Magneto leads the mutants, they are behind a force wall weaved together by alpha class mutants to cut them off and protect them from humanity.  Legacy(Rogue) is on the run from them. Last chapter she found Professor X and absorbed his abilities. So what is the history here and how did they end up in the predicament that their in?  Good story thus far, just got some questions to be answered.