Léon, the top hit man in New York, has earned a rep as an effective "cleaner". But when his next-door neighbors are wiped out by a loose-cannon DEA agent, he becomes the unwilling custodian of 12-year-old Mathilda. Before long, Mathilda's thoughts turn to revenge, and she considers following in Léon's footsteps.

Dave Lizewski is an unnoticed high school student and comic book fan who one day decides to become a super-hero, even though he has no powers, training or meaningful reason to do so.