Ultimate Fantastic Four / X-Men #2

The mutant-finding machine supreme—Cerebro—is in the devious hands of the Mad Thinker, who, with her newly acquired powers, seems impossible to thwart! Even the combined strength of the Fantastic Four and the X-Men mean nothing in this epic conflict. But will a chance for victory come from the most unexpected source imaginable? It's an ultimate shocker as we conclude this special crossover!

Characters: Colossus, Cyclops, Franklin Storm, Human Torch, Iceman, Invisible Woman, Jean Grey, Kitty Pryde, Mad Thinker, Mister Fantastic, Nightcrawler, Professor X, Thing, Wolverine