Though the classic coming-of-age story has become predictably banal, writer-director Mike Mills’ “Thumbsucker” infuses it with new life. Unfairly categorized as a typical teenage angst fare, “Thumbsucker” addresses a number of serious issues with staggering sincerity. Yet the film owes most of its success to the dynamic talent of lead actor Lou Pucci, whose pale, hollow-cheeked face is perpetually obscured by an adrift curtain of long brown hair. Perhaps one of the more promising up-and-comers, Pucci’s performance as Justin Cobb is both carefully understated and executed with an attention to detail that gives his character a sharp authenticity.

Shot beneath muted color filters, the film bears aesthetic similarities to both “Napoleon Dynamite” and Shane Carruth’s “Primer.” If anything, the insipid palette echoes the subdued character of Cobb, a high school anomaly who escapes the pressures of adolescence by sucking his thumb. His addiction invokes the pity of his mother (Tilda Swinton, who resembles Pucci to an uncanny degree, right down to the same stray lock of hair) and the annoyance of his well-meaning, but nevertheless judgmental, father (Vincent D’Onofrio). Yet, luckily, Keanu Reeves convinces Justin that his thumb tastes like echinacea.

Justin’s guru-orthodontist (Reeves, with unexpected wit and ample self-mockery) attempts to wean him from his thumb with hypnotherapy. Although the hypnotherapy proves to be somewhat successful, it is not until the nurse at Justin’s suburban Oregon high school suggests he take Ritalin that things really begin to turn around. Justin’s post-Ritalin life becomes so instantaneously wonderful that he is like a walking ad for the joys of pharmaceuticals.

Yet it is through this contrived plot twist that the film arrives at its biggest faults. The dramatic change is so outlandish and abrupt that the audience might find it a hard pill to swallow. Not only unrealistic, the transformation rings false in a film that otherwise manages to stay relatively true to human nature. By substituting Ritalin for his thumb, Justin suddenly and dramatically transforms from awkwardly anti-social to brilliantly eloquent, leading his high school debate team to the state championships. Perhaps these plot-related drawbacks are a fault of Walter Kirn’s book, on which the movie was based, rather than a defect of the film itself. Either way, though, Pucci manages to maintain the integrity of Justin’s character throughout the film.

Just as quickly as he is catapulted into a world of exaggerated happiness and ease, Justin promptly returns to reality after realizing that the Ritalin is merely a substitute for his thumb. So while the film flirts with the potential disaster of an overly manufactured and all too convenient ending, Mills artfully steers “Thumbsucker” away from such a cliched pitfall in the coming-of-age micro-epic genre.

Though in all fairness, the movie does end with Justin running through the streets of New York City (à la Kieran Culkin in “Igby Goes Down”) celebrating his acceptance to NYU and his newfound freedom from the oppression of Pacific coast suburbia that drove him to suck his thumb for all those years in the first place.

What makes “Thumbsucker” truly remarkable, and Justin’s character irresistibly introspective, is that Justin is able to recognize that while he may not have the answers, neither does anyone else — questioning life’s obscurities is hardly exclusive to the teenage condition. Mike Cobb, Justin’s dad, is still coping with a pro-football career that ended before it began; and Justin’s mother seeks to distract herself from the tedium of suburban life by entering a cereal box contest to win a date with a Tom Cruise-esque movie star with Robert Downey Jr-esque problems.

Thus, while “Thumbsucker” can be characterized as a coming-of age story, it radically deviates from the other films of its genre. Mills’s story deflects the cliche that growing up brings about resolve and, rather, acknowledges the universality of life’s persisting problems and the necessity for individualized solutions.

In the end, is thumb-sucking really more deleterious than a bottle of Ritalin? Tom Cruise would be proud.