We don't know when it happened, but it did. It started without anyone really noticing. Scientists making incredible breakthroughs in technological, biological, geological, and every other branch conceivable. Some of them figured out how to control things using their technology. It started with the what is now known as the first real life super villain Apocalypse. Modern weapons were useless. We had turned to the other scientists, where one stood out among the rest. He had made a suit powered by the very essence of life. He became the first super hero known as Genesis. It wasn't long after that when we finally realized what hit us. Mutations began becoming apparent in some of the human populace. The fight between Genesis and Apocalypse had caused a surge of evolution in all of humanity. Most of us were unaffected, but it had become clear that the Human race was entering the Dawn of a New Age.
It's basically an alternate Earth History where something catastrophic occurred and the Human race had to suck it up and move on. Every one in one thousand humans had become mutants (A statistic that may or may not be accurate). Many of those who were down trodden used their new found power for their own gain. Some turned to heroics. Some of the mutant powers are completely illogical. Life moves on. The story focuses around the view points of various humans turned hero and villain as society is forced to take a look at what can happen when just one man can become an unstoppable army.