There’s no room for the hazy fictions of high-school movies in The Diary of a Teenage Girl, an honest and razor-sharp dissection of what it’s like to be a young woman on the cusp of her sexual awakening.

Perhaps “precipice” is a better word, because the movie’s protagonist, 15-year-old Minnie Goetz (British actress Bel Powley, in a gutsy, breakout performance), is not one for tentative first steps. When we first meet her, she’s gliding through a sunny park in bohemian 1976 San Francisco, grinning and self-assured and more than a little incredulous because, as her voiceover tells us, she’s just had sex for the first time. And she’s really, really happy about it.

So effervescent is Minnie that it’s impossible not to be happy right along with her. After all, teenage boys have been humping their way through movies for several generations now. But then she gets home, busts out a tape recorder and microphone, and begins an audio diary that clues us in on the identity of her lover: her mom’s 35-year-old boyfriend, Monroe (a slinky, ’stached-up Alexander Skarsgård).

Thus begins a messy, tumultuous coming-of-age story that shines a high-powered spotlight onto the darkest stretches that lie between adolescence and adulthood. It’s a very grown-up movie about what it feels like to grow up.

If Minnie’s earliest confession is upsetting—as it should be—you’re in for a bumpy ride. The film follows Minnie through awakenings of several varieties. She doesn’t get much guidance from adults—her libertine mom, Charlotte (Kristen Wiig, who’s proven to be an exceptional dramatic actress), snorts coke in front of her, and the closest thing she has to a father lives in New York.

She does get something of a fairy godmother, though, in the form of underground comix icon Aline Kominsky (contemporary and wife of R. Crumb), whose work has a huge influence on aspiring cartoonist Minnie. The film is often embellished with Minnie’s doodles, brought to life by animator Sara Gunnarsdóttir; Minnie sprouts glowing wings during an acid trip, and imagines cartoon penises tumbling from flies with silly “sproing” sounds. Occasionally the animation takes center stage as Minnie grows more confident as an artist, rendering herself as a cross between King Kong and the 50-Foot Woman as she stomps through San Francisco.

It makes for a film that’s as visually engaging as it is emotionally revealing and sometimes disturbing. Minnie’s unsavory, clandestine romance with Monroe, which continues throughout the movie, sets her on a winding path through San Francisco’s booming counterculture, with her best friend Kimmie (Madeleine Waters) at her side.

Is there any doubt such a scene has a grimy underbelly, and that Minnie and Kimmie will find it? Based on Phoebe Gloeckner’s 2002 graphic novel The Diary of a Teenage Girl: An Account in Words and Pictures and adapted for the screen by first-time director Marielle Heller, Diary is enthusiastically R-rated and sometimes uncomfortably graphic, but it’s never exploitative. It’s a raw but classy film about raw but skeezy topics.

It’s also worth noting that, though the subject matter is prickly even at its mildest, Diary never levels judgment toward any of its characters—not even Monroe (though it doesn’t whitewash his actions either). Nor does it paint Minnie as a victim, even when a lesser story would surely do so.

So this is no morality tale, and Diary is all the better for it. It’s just a story about growing up, and it’s very much Minnie’s story. But like all good flicks, it’s both intensely personal and profoundly universal. I don’t think it’s much of a spoiler to say that Minnie does find her way in the end, and that she turns out okay. Her closing dedication—“This is for all girls when they have grown”—might drive home the movie’s themes about owning one’s sexuality and taking charge of one’s one story, but the film’s clarity of vision makes such a coda almost redundant. Still, it’s a great line, and it makes for a groovy rallying call. 

April Snellings

April Snellings is a staff writer and project editor for Rue Morgue Magazine, which reaches more than 500,000 horror, thriller, and suspense fans across its media platforms. She recently joined the lineup of creators for Glass Eye Pix's acclaimed audio drama series Tales from Beyond the Pale, an Entertainment Weekly “Must List” pick that has been featured in The Wall Street Journal and The New York Times.