Dave Lizewski, a teenager and high school nerd in New York is an avid comic book reader, but is unpopular at school. His companions in comic book fanaticism are Marty and Todd. Dave also has a crush on Katie Deauxma but goes unnoticed most of the time. Having been a loser most of his life, he takes some decisions. He is determined to become a super hero and calls himself "Kick Ass". But...

Dave Lizewski, a teenager and high school nerd in New York is an avid comic book reader, but is unpopular at school. His companions in comic book fanaticism are Marty and Todd. Dave also has a crush on Katie Deauxma but goes unnoticed most of the time. Having been a loser most of his life, he takes some decisions. He is determined to become a super hero and calls himself "Kick Ass". But he is injured in the very first attempt at being a hero. After he is sent to the hospital, Katie starts noticing him. At another part of the city an ex-cop is trying to catch a well-known criminal Frank D'Amico and trains his eleven year old daughter Mindy as a vigilante. When Dave's, Mindy's and Frank's paths cross, there are misunderstandings that develop. Frank believes that Kick Ass is after his life and plans to destroy him instead of Mindy.