When Senator Robert Kelly wants to be the next President of the United States, the Brotherhood of Mutants tries to kill him again (the Brotherhood had a failed assassination attempt in the Days of Future Past story arc). But Mystique intends more than just assassinating Kelly, and she has got something up her sleeve! She has an altered Legacy Virus, originally designed to kill mutants, which only affect those without the mutant gene (that means every human in the world)! The X-men split into two forces. Cable, Gambit, Beast and Colossus are protecting Senator Kelly from the reformed Brotherhood of Mutants in Boston. In the meantime Wolverine, Bishop and Rogue are trying to find out what Mystique is doing on Muir Island.
The main events of the crossover are the deaths of Pyro, Moira MacTaggert and Senator Robert Kelly.