The fate of the entire Marvel Universe hangs in the balance as Earth's mightiest heroes face their greatest challenge! Summoned across the stars by the mysterious and unbelievably powerful Beyonder, the Avengers, Spider-Man, the Fantastic Four, and the X-Men are set against their deadliest foes on the mysterious planet known as Battleworld - with the winner promised the ultimate prize. But as battle lines are drawn, new alliances are forged, and old enemies clash, one among them is not willing to settle for anything less than godhood.

Iron Man and Captain America are two core members of the Avengers, the world's greatest superhero team. But when a tragic battle blows a hole in the city of Stamford, killing hundreds of people, the US government demands that all superheroes unmask and register their powers. To Tony Stark - Iron Man - it's a regrettable but necessary step. To Captain America, it's an unbearable assault on civil liberties.

When Eddie Brock becomes biologically linked to a bizarre alien symbiote, the two share a common goal. At first, they seek to squash their arch-foe Spider-Man. But after repeated attempts, Venom reaches an uneasy truce with the web-spinner. Brock leaves New York and heads west to San Francisco, the city of his birth, eager to put trouble behind him, but trouble has different ideas. Brock commits himself to becoming a defender of the innocent, but he's a six-foot-three-inch, 260 lb. figure with bulging muscles and fangs like a shark. Venom quickly draws attention.

The X-Men are mutants—born with extraordinary powers that set them apart from the very humanity they are sworn to protect. Now, groundbreaking research has revealed a method for reversing the genetic mutation responsible for mutant powers—whether the mutant wants it reversed or not. The US government wants to use this procedure to eliminate the so-called mutant menace once and for all—but the X-Men soon learn that the true source of the procedure is their old enemy, Sinister! And his agenda is far more complex and dangerous than even the X-Men can imagine.

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.