The recent surprise box-office hit "Paul Blart: Mall Cop" has one thing in common with "Observe and Report": a plot involving a lowly retail security guard who yearns to be a hero by capturing an on-the-loose criminal lurking on the premises. That is where the similarities stop. Whereas the former film was tepid, tame and grindingly conventional, the latter is an utterly unapologetic, anarchist comedy, as black as charcoal and steering in directions that studio pictures rarely have the courage of their convictions to go. Snappily written and directed by Jody Hill (2008's "The Foot Fist Way"), the movie journeys all over the map and never exactly decides what it wants to be—and that's the grotesque charm of it all. Instead of painting itself in a clearly rendered box, "Observe and Report" is free to touch upon ribald, at times vicious, humor surrounded by helpings of pathos, tragedy, and brutal spurts of violence. The material is ultimately strong enough to withhold these differing tones, and is better for it.

When no less than fifteen women are accosted in the parking lot by a serial flasher, Forest Ridge Mall security guard Ronnie Barnhardt (Seth Rogen) makes it his mission to track down the perpetrator. With few leads and yet another victim coming forward in the form of Ronnie's longtime crush, make-up counter girl Brandi (Anna Faris), Detective Harrison (Ray Liotta) is called in to investigate. Resentful and insulted, Ronnie isn't about to let Harrison steal his thunder on the case. And, once he stops taking his meds to treat his bipolar disorder, all bets are off.

The premise of "Observe and Report" does not nearly do justice to its cinematic treatment, which is independent in flavor, gloriously rebellious in spirit, and uncompromising in its view of an insular world where one's humanity (or lack thereof) is seen in all of its bared ugliness. The flasher, who runs amok just out of the grasp of authority, is more or less a plot device serving to mentally derail Ronnie, who is sick and tired of being looked down upon by working mall security. In a bid to better himself, he tries to join the police force, and would be an ideal candidate if he didn't reveal how crazy he was to the therapist responsible for his psychiatric evaluation. At the end of his ropes over being rejected time and again—his date with Brandi leads to a dead end, too, when she reveals herself to be nothing more than a belligerent, barbituates-popping floozy—Ronnie self-destructs into a modern-day Travis Bickle, wading into hard drugs and alcohol abuse via wayward Mexican mall cop Dennis (Michael Pena) and then flirting with grisly acts of violence.

Yet, amidst all of this behavior, Ronnie remains somehow likable—if not virtuous, then at least someone worth rooting for. His bipolar traits are clear, but there is a dignity in the way that, when it comes right down to it, all he really wants is to do good and be respected. Seth Rogen (2008's "Pineapple Express") is perfect as Ronnie in what could be the actor's most accomplished and complex performance, to date. Rogen's natural affability aids in making Ronnie relatable and sort of sad—a young man who can't quite find levity in his troubled life no matter how hard he tries. His relationship with his boozy mother (Celia Weston), drinking herself into a stupor in between conversations that usually end with her spouting hurtful truths to her son, is painfully funny and then rather touching by the end. She loves Ronnie, to be sure, but isn't above softly telling him that he's the reason his father ran out on the family years ago. Celia Weston (2007's "The Invasion") is comic gold as Ronnie's mom, but also more than that, turning what could have been a caricature into a three-dimensional character by the end.

Other acting turns are sharply realized by an ace ensemble. Not typically known for his comedic skills, Michael Pena (2007's "Lions for Lambs") lingers subtly on the sidelines as Dennis, but eventually comes into his own when Ronnie temporarily befriends him and key revelations are discovered about who he really is behind closed doors. Collette Wolfe (2008's "Four Christmases") is a radiant find as Nell, a physically debilitated food court worker who takes a liking to Ronnie while the rest of her coworkers blatantly make fun of her to her face. As dream-girl-with-fangs Brandi, the invaluable Anna Faris (2008's "The House Bunny") embraces with all of her might the chance to play someone less than kind. Brandi's date with Ronnie, which goes from uncomfortable to hedonistically joyous to downright appalling as she drinks and pill-pops herself into oblivion, is easily one of the film's highlights, and Faris milks it for all it's worth.

Mainstream audiences looking for safe entertainment will be at a loss for what "Observe and Report" offers. The film, at once hilarious, frightful and recklessly inventive, makes no apologies, and concludes on a twisted note of triumph that is upbeat in the same way John Waters' "Pink Flamingos" might be considered happy. Above all, writer-director Jody Hill, finding laughs in the perverse and surprising breaths of drama in its starkness, is a filmmaking talent to watch out for. His use of music—from the folksy, borderline-whimsical score by Joseph Stephens, to quirky choice soundtrack cuts by The Band, The Yardbirds, Little River Band, and City Wolf (performing a cover of The Pixies' "Where Is My Mind?")—indelibly services the images, photographed with flair and aplomb by cinematographer Tim Orr (2008's "Sex Drive"). Meanwhile, Hill's script is layered enough that the random tangents he goes off on nevertheless feel as if there is a method to his loose style. "Observe and Report" is far from a cheery romp, but who says it has to be? By taking chances and freeing itself of a safety net, the picture arrives as a welcome respite to the same-old, same-old.