In "Diary of a Teenage Girl," a bell-bottomed California 15-year-old girl comes of age in 1970s San Francisco. She documents the transition she's been craving, narrating into a tape recorder her eager plunge into sex and adulthood, and illustrating it in crude cartoons that take after R. Crumb.
The awakening of Minnie Goetze (23-year-old Bel Powley) is awkward and brash, enthusiastic and angst-ridden, lewd and tender. And it's gloriously honest.
As a film made by women and starring a female protagonist, "Diary of a Teenage Girl" is a bracingly fresh entry in a coming-of-age tradition that has, in the movies, almost always been seen through male eyes. It's an unusually accomplished first film from Marielle Heller, who also wrote the screenplay, an adaptation of Phoebe Gloeckner's 2002 graphic novel.
The different perspective is clear from the first shot, in which Heller, in close-up, trails from behind and below the hippy strut of Minnie. She narrates: "I had sex today. Holy s---." Minnie smiles to herself, but her glow momentarily fades when a buxom blonde jogs past her.
Such fleeting, contrary emotions of exuberance and self-doubt pinball throughout "Diary of a Teenage Girl," a movie with a firm grip on how it feels to be a precocious 15-year-old in burning pursuit of self-discovery.
She finds much of it within her family's wall-papered, second-floor San Francisco apartment, where she lives with her mom, Charlotte (Kristen Wiig), and little sister, Gretal (Abby Wait). The air is filled with cigarette smoke, California sunlight and the moral muddiness of post-60s, Patty Hearst-era 1976. After a string of men, her mom is "looser now," Minnie says. She vacuums during coke-fueled cleaning binges.
Minnie, big-eyed with dark bangs, is told she "exudes sexuality." Her first sexual experience, and one that continues throughout the film, is with her mother's 35-year-old easy-going, beer-drinking boyfriend, Monroe (a striking, naturally charismatic Alexander Skarsgard). What begins with childlike playfulness begets a full-blown affair.
The age difference, of course, makes the relationship inappropriate, but "Diary" largely withholds that judgment. Minnie is the one who's choosing her partners and driving her story. After their first time in bed, she asks Monroe to take a polaroid of her, so she can see how she's changed. She deduces she looks different: "probably my aura."
In her headlong rush into adulthood, she passes by the boys of her high school. One is frightened by her experienced prowess in bed. The escapades grow darker, too, in the chapter she introduces as "The Making of a Harlot." The sole grounding voice in her life is her former stepfather Pascal (Christopher Meloni), who makes comic but heartfelt attempts to sternly instruct Minnie and Gretal.
The whole ensemble is excellent, but the film belongs to newcomer Powley, who doesn't so much play Minnie as become her. Her performance is remarkably easy in its intimacy, filled with moments like gazing skeptically at her naked body in the mirror and jumping on her bed with a friend to Iggy Pop and the Stooges.
Female sexuality has typically been so constrained by the movies that "Diary of a Teenage Girl" feels almost radical in its portrait of empowering promiscuity.
Heller occasionally overlays the film with bits of psychedelic animations by Sara Gunnarsdottir, a technique that has become to feel a little overused. Minnie aspires to become a cartoonist like Aline Kominsky, R. Crumb's future wife, who, herself, succeeded in the male-driven comic book industry.
But thank goodness the irreverent but earnest "Diary of a Teenage Girl" avoids the moralizing that would usually accompany a film about young people, sex and drugs. Besides, Minnie is too busy growing up to get bogged down in such things, too busy haplessly becoming one of the most memorable protagonists of the year.
"Diary of a Teenage Girl," a Sony Pictures Classics release, is rated R by the Motion Picture Association of America for "strong sexual content including dialogue, graphic nudity, drug use, language and drinking involving teens." Running time: 102 minutes. Three and a half stars out of four.
Follow AP Film Writer Jake Coyle on Twitter at: http://twitter.com/jakecoyleAP