C I V I L W A R
In summary, an explosion in Stamford by the villain Nitro causes the US Government to introduce Superhero Registration Act. Those not adhering to it are deemed unregistered and rogue superheroes. Tony Stark and Dr Reed Richards lead the side of the pro-registration superhero. Captain America leads the anti-registration side. Spider-Man, initially with Tony Stark, eventually joins the team of Captain America. Goliath is killed by the pro-registration superheroes. Many super-villains join the Government in hunting down superheroes.