Hapless teen Dave Lizewski (Johnson) decides to man up and fight crime as a costumed vigilante, Kick-Ass. After first becoming an internet phenomenon, he quickly bites off more than he can chew when he falls foul of a ruthless mobster, but two genuine superheroes, Big Daddy (Cage) and his daughter, Hit-Girl (Moretz), may hold the key to salvation. And kicking ass.