The X-Men—mutant protectors of a world that fears and hates them. The Avengers—Earth's mightiest heroes, the greatest super-team ever assembled. When the Scarlet Witch of the Avengers and Rogue of the X-Men all disappear under mysterious circumstances, each team's search leads them to more questions than answers. When the X-Men appear to attack a high-security government installation, the Avengers must track down the mutants, and learn the truth behind the abductions before it's too late

With the help of the Incredible Hulk, the Avengers and the X-men set out to find the Leader, the gamma-powered evil genius who abducted two of their teammates—but the Leader has the power of the Gamma Sentinels behind him