With her Eastwood-worthy snarl, a purple wig that would do a Vegas stripper proud, and the martial arts chops of a John Woo assassin, 11-year-old Mindy Macready, also known as Hit Girl, is a force to be reckoned with.

A potty-mouthed pip-squeak trained in weaponry and weird sidelong glances by her cop-turned-vigilante freakazoid father - Big Daddy, played with typically nutty gusto by Nicolas Cage - Mindy doesn't have the title role in Kick-Ass, but her presence is everything. Chloe Moretz, a 13-year-old who has already amassed more than 30 credits on her IMDB page, gives a performance of prodigious cool.

Pushing several envelopes (extreme violence, extreme profanity, extreme smartaleckyness) and juggling teen angst comedy with superhero fantasy, Kick-Ass has been adapted from the Mark Millar/John Romita Jr. comic book in nimble fashion by British director Matthew Vaughn.

It's the story of Dave Lizewski (Aaron Johnson), a dweeby New York City high schooler who decides to become a superhero - even though he hasn't been bitten by a radioactive spider, or sent here from Krypton, or even put in much time at the gym. Later in the film, this fact results in an astute voice-over observation from our would-be hero: "With no power comes no responsibility."

But Dave, who has a pair of comic book-obsessed nerd buddies and an unrequited crush on a classmate (the pert Lyndsy Fonseca), customizes a wet suit and goes out on the crime-ridden streets anyway. Armed with a couple of batons and "the perfect combination of optimism and naivete," Dave dubs himself Kick-Ass. And after he gets those words reversed on him in front of a doughnut shop crowd, videos of his valiant effort to save a guy from a mugging become a viral sensation. A YouTube phenom is born.

As fate (and Jane Goldman and Vaughn's canny screenplay) would have it, Kick-Ass unites with Hit Girl and Big Daddy to do battle against gangland boss Frank D'Amico (a mobbed-up Mark Strong, the villain in Sherlock Holmes). Meanwhile, D'Amico's sheltered, sourpuss son, Chris (Superbad's McLovin, Christopher Mintz-Plasse), has dreams of being a caped dude, too. Enter Red Mist, looking like a Kiss tribute band reject.

Kick-Ass has punk energy, ace action moves, and a winning sense of absurdist fun. The film wittily references Billy Wilder's Sunset Boulevard, Frank Miller's Sin City, and Ennio Morricone's spaghetti western scores (among many other films, TV shows, music, and comics). If its depiction of high school life feels cliched - lunchroom pecking orders, Internet porn masturbation jokes - those cliches have everything to do with why Dave puts on a mask and a green-and-yellow costume and busts out of there.

Does the spectacle of a preteen in pigtails slinging ninja stars and nasty epithets feel exploitive, or inappropriate, or appear to be a sign that the end of civilization is upon us? Well, in Vaughn's hands - and Moretz's ridiculously assured turn - the question is moot. Sure, Hit Girl's wild and woolly behavior shocks and startles, but that's the idea.

She pulls it off with impudence and impunity - and so does the movie.EndText

Contact movie critic Steven Rea at 215-854-5629 or srea@phillynews.com. Read his blog, "On Movies Online," at www.philly.com/philly/blogs/onmovies.