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.

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.

In a Manhattan warehouse, an innocent man has been murdered during a mysterious crime. Evidence points to the involvement of Venom - the alien symbiote obsessed with Spider-Man's destruction. Yet Venom has always safeguarded innocent lives. Has Venom gone completely around the bend, or is there another suspect? Spider-Man thinks there is more to the crime than meets the eye. The specter of the Hobgoblin, one of Spider-Man's nastiest foes, falls on a series of thefts and leads the web-slinger to a deadly secret that may cause New York's destruction.

A vicious serial killer named Cletus Kasady has had his body chemistry altered by an alien creature. Now, Kasady can transform into Carnage, who, along with his lethal living costume, lives for chaos and random acts of senseless, brutal murder! Carnage has been returned to New York in chains, the subject of a daring attempt to reverse the effects of his metamorphosis. When the interference of a deranged scientist causes the experiment to go horribly wrong, Carnage is set loose upon the city once again!

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.