American comedies have spent the last few years exploring the idea of the man-child — physically mature, but mentally stuck somewhere between high school and adulthood. Now we meet his female counterpart, and it’s not a pretty sight. So much the better: Reteaming pop-savvy scribe Diablo Cody with “Juno” director Jason Reitman, “Young Adult” revels in breaking the rules of safe Hollywood storytelling, casting Charlize Theron as an emotionally stunted YA novelist with limited appeal and no tidy character arc. A B.O. gamble, the deliberately prickly pic courageously risks offending audiences to arrive at a truth beyond its genre’s normal grasp.

Cody has found herself in the media crosshairs after the overnight acclaim of “Juno,” and though the snark-meister has managed to sustain her unique brand through a mix of Twitter updates, Entertainment Weekly columns and edgy writing assignments (“Jennifer’s Body,” “The United States of Tara”), “Young Adult” will surely be the make-it-or-break-it project in many people’s estimation of her talents. Rather than play it safe, Cody spins a personal case of writer’s block — possibly inspired by her gig adapting “Sweet Valley High” for screen — into a deeply unflattering, semi-autobiographical takedown of adult-onset insecurity and egotism, inventing the story of a self-absorbed teen-lit novelist who returns home to rekindle things with the now-married boyfriend she dated in high school.

Theron plays Mavis Gary — beautiful, successful and a mess. Mavis long ago achieved her goal of escaping the perceived oppression of small-town Mercury, Minn., to live the dream in Minneapolis. So why is she so unhappy? “Young Adult” is hip to the answer, but never preaches it outright: When people can hardly stand to be around themselves, they continue to run from and reinvent their lives until they address the fact that the root of their dissatisfaction lies within.

Though Mavis is undoubtedly fashioned from aspects of her creator’s own personality, the operating idea here seems to be that people don’t change. The high-school queen bee will always be insufferable, and her fitting punishment will be having to live with herself — which is precisely Mavis’ situation when the film opens: divorced and getting by on TV dinners and one-night stands in a dumpy caricature of her cosmopolitan ideal.

In such straits, an innocuous email announcing the birth of her old flame’s baby is all it takes to send Mavis’ mind back to the glory days, when she and football star Buddy Slade (Patrick Wilson, reprising his laid-back “prom king” aura from “Little Children”) were the school’s cutest couple. On the surface, “Young Adult” is about Mavis’ delusional quest to steal her former beau away from new wife Beth (Elizabeth Reaser in a sly supporting turn). Deeper down, the film engages with the concept of maturity in a culture that celebrates such youthful ideals as beauty and instant gratification.

In Mavis’ case, writing pulp melodramas for the Noxzema set encourages her to stay stuck in an adolescent mindset. However, since comedy is tragedy that happens to other people, the film easily plays as satire, following in the same vein as Alexander Payne’s shrewdly observant, gently condescending Midwestern portraits, featuring character moments so true, one can’t help but laugh in pained recognition.

While Cody settles on a less singular yet still piquant voice for her contempo characters than the one heard in “Juno,” Reitman and his cast expertly manage the film’s tricky tone. Even so, “Young Adult” seems content to remain small, retreating from Mavis’ climactic moment of catharsis to deliver an ending that breaks yet another long-standing Hollywood rule, as the flawed heroine stares self-realization in the face and consciously decides not to learn from her experience.

In a film intent on authenticity, it’s no coincidence that Mavis seems to be surrounded by inane reality-TV programming. Real life is messier than that, as demonstrated by the film’s most sympathetic character, a former classmate named Matt Freehauf who was crippled by the cool kids during a miscalculated gay-bashing incident. In a poignant, career-redefining performance by comedian Patton Oswalt, Matt has every right to be resentful, and yet, he’s coped with his adolescent issues better than Mavis.

Mavis, by contrast, comes across like a vampire straight out of one of the supernatural YA book series so popular these days. Shying away from the sun, she eavesdrops on real teens for story ideas and stalks Buddy and his new family, oblivious to the damage she’s capable of inflicting on others.

For Theron, this represents a different kind of performance from “Monster” and “North Country,” for which she won plaudits while allowing herself to look superficially unattractive. Here, the actress plays closer to home, inviting auds to observe the process by which she makes herself beautiful, painting on makeup, clipping her nails and attaching hair extensions to disguise her physical flaws. But the scowl etched on her face reveals the ugliness within, demonstrating a naked candor — one that extends to the screenplay itself — that’s plenty admirable, in part because it’s so squirm-inducing to behold.

Young Adult

  • Production: A Paramount release presented with Mandate Pictures of a Mr. Mudd production in association with Right of Way Films and Denver & Delilah Films. Produced by Lianne Halfon, Russell Smith, Diablo Cody, Mason Novick, Jason Reitman. Executive producers, Nathan Kahane, John Malkovich, Steven Rales, Helen Estabrook. Co-producers, Kelli Konop, Mary Lee, Beth Kono. Directed by Jason Reitman. Screenplay, Diablo Cody.
  • Crew: Camera (Deluxe color), Eric Steelberg; editor, Dana E. Glauberman; music, Rolfe Kent; music supervisor, Linda Cohen; production designer, Kevin Thompson; art director, Michael Ahern; set decorator, Carrie Stewart; costume designer, David Robinson; sound (Dolby Digital/Datasat/SDDS), Ken Ishii; supervising sound editors, Warren Shaw, Perry Robertson, Scott Sanders; re-recording mixers, Michael Barry, Eric Hirsch; visual effects supervisor, John Bair; visual effects, Phosphene; stunt coordinator, Peter Bucossi; assistant director, Jason A. Blumenfield; casting, Suzanne Smith Crowley, Jessica Kelly. Reviewed at DGA Theater, Los Angeles, Nov. 15, 2011. MPAA Rating: R. Running time: 93 MIN.
  • With: Mavis Gary - Charlize Theron Matt Freehauf - Patton Oswalt Buddy Slade - Patrick Wilson Beth Slade - Elizabeth Reaser Sandra Freehauf - Collette Wolfe Hedda Gary - Jill Eikenberry David Gary - Richard Bekins Jan - Mary Beth Hurt