Justin Cobb (Lou Pucci, “The Chumscrubber”) is 17. He’s not doing well in school. His parents, former football star Mike (Vincent D’Onofrio, “Law & Order: Criminal Intent”), who’s shot at the pros was undone by a knee injury, and Audrey (Tilda Swinton, “Broken Flowers”), who’s obsessed with a television heartthrob (Benjamin Bratt), think he’s underperforming. His debate teacher Mr. Geary (Vince Vaughn, “Wedding Crashers”) thinks he has trouble concentrating and might have ADHD. His New Age orthodontist Perry (Keanu Reeves, “The Matrix”) thinks he needs to lighten up and connect with his inner spirit animal. Little brother Joey (newcomer Chase Offerle) doesn’t care what the others think, he just wishes Justin would stop being so weird so he could have a chance to let lose and not have to be the normal one all the time.

Oh. One more thing. He still sucks his thumb.

It’s a lot, and Justin isn’t too sure any of them have the right answers to help him out. What he is sure of is that all of them are every bit as insecure about their lives as he is about his own, and while he may look like idiot sucking his thumb at least he’s upfront about what’s going on. Heck, even the girl of his dreams can’t admit what’s wrong in with her own life, fellow high school senior Rebecca (Kelli Garner, “The Aviator”) hiding her insecurities about sex and relationships behind a coolly indifferent demeanor that’s nothing more than a transparently cloudy smoke screen.

Based on the acclaimed semi-autobiographical novel by Walter Kim, “Thumbsucker” is a tough and uncompromising coming-of-age piece every bit as prickly and hard to warm up to as its protagonist. The debut motion picture by acclaimed commercial and video director Mike Mills, this movie is a rough, complicated social satire full of bumps and bruises and obtuse corners so many other features go out of their way stay away from. In this case, though, that disjointedness is all to the good, Mills achieving and intimacy and a connection with his main character that’s as solid as the proverbial rock.

It helps that he has a star-making performance by young Pucci. Winner of a Special Jury Prize for Acting at Sundance and named Best Actor at the Berlin International Film Festive, the kid is the real-deal galvanizing the film with his complex charm and dynamic everyman good looks. Whether sucking his thumb, chomping down on Ritalin, delivering the knock-out punch in a debate or soulfully trying to convince his mother things are going to be okay, this kid can do no wrong. In a movie covering more hot-button issues that an episode of “Oprah,” Pucci delivers a performance bordering on spectacular, and as good as the rest of the cast is there is no way “Thumbsucker” would work half as well without him.

The rest of the actors are good, though, especially those playing the Cobb family. D’Onofrio, Swinton and Offerle share a chemistry with Pucci that’s magnetic, the four of them feeling so much like kin it’s almost a shock to realize they’re not actually related. Each has their moments, but none ever overpowers the others, all of them working in delicate symmetry to create a multifaceted symphony feeling so lived in and alive I could almost imagine the whole group living right next door.

While it is certainly a fact not much here is original, we did just see the whole suburban-youth-pharmaceutical-alienation thing with “The Chumscrubber” and “Garden State” after all, that doesn’t make it any less effective. While the other recent pictures trafficked in the surreal, “Thumbsucker” feels genuine. Mills takes both the piece and his characters seriously, investing them all with the observational warmth and care of a documentarian trying to understand the complex differences making up a dysfunctional-yet-loving family.

It’s all a bit disconcerting, and I mean that a compliment. Mills has adapted Kim’s stories beautifully, touching all the labyrinthine dynamics that make them a must-read. Some of it doesn’t work, I’m not entirely sure I bought Justin’s dalliance with marijuana or a late-night chat with Bratt’s television star, and the film isn’t very visually interesting. But it does make a person think, the whole thing more alive that just about any other melodrama I’ve seen this year, Pucci and Mills transporting viewers into a world that somehow feels uncomfortably much like their own.

Obviously, this will not be everyone’s cup of tea. But it is mine and as I’m the one writing the review that’s going to have to be good enough. In fact, there were moments as I watched “Thumbsucker” I couldn’t help feel it bordered on the brilliant. Well, maybe not overall but definitely in bits and pieces, while Pucci’s performance certainly is in its entirety. One thing’s for sure, of all the things a person can think to say about this movie one they certainly can’t, title to the contrary, is that it sucks.

Film Rating: êêê1/2  (out of 4)