After a disastrous intervention by the New Warriors in Stamford results in the deaths of hundreds of civilians, the United States government passes a law requiring superheroes to reveal their identities and register with the authorities. Iron Man supports the measure, believing that oversight is necessary to prevent further tragedies, while Captain America refuses to sacrifice individual freedoms in the name of security. Their disagreement deeply divides the superhero community and turns former allies into enemies. Spider-Man, the Avengers, and many other heroes must choose a side as confrontations escalate and the consequences of the conflict threaten to permanently reshape the Marvel Universe.