After Kick-Ass' retirement, new heroes rise but face the wrath of Red Mist and his gang of villains. Kick-Ass joins Justice Forever, while Mindy struggles with isolation. The Motherf****r seeks revenge on Kick-Ass and his loved ones. As friendships crumble and battles ensue, Kick-Ass must step up to become the hero the city needs.

Dave Lizewski, a comic book fan, decides to become a superhero named Kick Ass. He orders a suit online and starts fighting crime. After surviving a brutal stabbing, he gains popularity on the internet. Meanwhile, a father-daughter duo, Big Daddy and Hit Girl, are also fighting crime. They join forces with Kick Ass to take down a local mobster, Frank D'Amico. In the end, Kick Ass, Hit Girl, and Big Daddy defeat D'Amico, but Chris, Big Daddy's son, becomes the new supervillain, seeking revenge.