Splintered and alienated, the forces of Avengers and X-Men stand on opposing sides. The Red Skull has been released from his holding cell in Avengers Tower. Someone aided him. Someone who was present on Genosha. But whom? And why are the heroes and villains acting so strangely?

Narrowly escaping with their lives, Spider-Man and Nova are enlisted by Steve Rogers for a daring mission that could determine the fate of us all. The new Sorceress Supreme finally gains her revenge against the benevolent Doctor Doom. The Superior Iron Man battles Daredevil for the fate of an Extremis infected San Francisco. And in the name of survival of the fittest, the X-Men claim their new home.