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 - 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 as ULTIMATE FANTASTIC FOUR's Mike Cary is joined by superstar artist Pasqual Ferry for this tour de force of Ultimate action! Plus: in-depth bios on the Ultimate X-Men, the Ultimate Fantastic Four, the Ultimates and Ultimate Spider-Man!