Cerebro has been stolen ? and the trail points directly at the government?s premier think tank, the Baxter Building! The X-Men aren?t happy about it ? especially after the shattering events of last month?s Ultimate X-Men issue. And the Baxter Building?s most famous residents ? the Fantastic Four ? aren?t happy about an angry team of mutants showing up on their doorstep! It?s FF versus X-Men in an all-star blowout that leads directly into next month?s Ultimate Fantastic Four / X-Men!