As superheroes Kick-Ass and Killer, the couple fought fiercely with the underworld, getting some problems in parallel. Now Kick-Ass' girlfriend, 15-year-old Killer, is at a crossroads: after they can no longer save Big Daddy, her guardian, Detective Marcus Williams, demands that Mindy Macready act like a normal teenager. Dave Lizewski also promises to give up his father in order to take off his superhero costume. But, despite the hard everyday school life, both feel the desire to do something more, especially since their exploits have spawned many imitators.
So the teenagers were recruited by Sal Bertolini, a former criminal who now fights injustice as Colonel America. Under his leadership is the Justice Forever superhero squad and his dog, Eisenhower. Kick-Ass and Killer join Sal, but they are forced to deal with an old, vengeful nemesis: Chris D'Amico wants to avenge his father's death. Chris gathers an "army of evil" around him, and in the role of Maza-Rashi, ex-KGB agent Ekaterina Dubrovsky, he gets a powerful ally. Thus, both sides soon engaged in fierce fighting and gradually confused the police in this war, which as a result decided to arrest all those wearing masks.