After the New Warriors go after a group of Villains in Stamford, Connecticut, Nitro detonates, killing 600 people in the process. This prompts the Government to enact the Superhuman Registration Act, forcing heroes to register with the government, revealing their identities. Some such as Iron Man, Mister Fantastic, and Black Widow are quick to comply. But Captain America believes that this goes against everything that America was built upon and that this is a way for the Government to tell people who the bad guys are. So he rallies up some Allie’s to join his underground movement and combat this.
