Don't let the title fool you. The Diary of a Teenage Girl brings to mind some kind of cutesy claptrap without any depth, the type of movie independent film fans fervently avoid -- when it's in fact exactly the kind of movie such people should and will want to see.
One key difference, among many, is that this "Diary" comes from 1970s San Francisco, and the teenage girl in question is Minnie, played by the phenomenal Bel Powley. Actually 23 years old, she is utterly convincing as a 15-year-old girl suddenly obsessed with sex. That is, in fact, the opening line of the movie: "I had sex today." Her attitude, her demeanor, her approach -- all of this is informed by the time and place in which she exists, walking through the park among other people sitting in the grass, casually doing drugs or hanging out topless (or both). She's not really thinking about them. She's thinking about sex with her mother's boyfriend.
Oh, did I mention it's also more than a little creepy? Director Marielle Heller, who also wrote the script adapted from the novel, does an impressive job of straddling the fine line between creepy and sweet -- because much of this is sweet, too. It makes for a lot of uncomfortable viewing. This dynamic is also much informed by the seventies setting: far more people today would be horrified by a 35-year-old man having sex with a 15-year-old than would have been then.
Minnie does not have the most attentive mother. Charlotte, played by Kristen Wiig in her best performance so far -- I would even go so far as to say it's worthy of an Oscar nomination -- spends a lot of time partying and doing drugs of her own. In some cases she and her daughter are doing drugs separately but at the same party. Charlotte clearly loves and cares for Minnie, but is a bit misguided in her approach. She encourages Minnie to flaunt her body more, to get the attention of boys. At first she has no clue that Minnie very much has the attention of her boyfriend, but that slowly starts to change.
Alexander Skarsgård plays the boyfriend, Monroe, who himself straddles the line between naïve and predatory. His and Minnie's relationship develops in a weirdly organic way, although it does begin with them snuggling on a couch in a way that has his hand on her breast. After that, Minnie is strikingly forward in her intentions on him -- she tells him outright that she wants him to fuck her. Monroe laughs it off at first, but doesn't exactly discourage her. He later claims she is manipulating him, and Minnie likely feels satisfied that that is exactly what she's doing. Neither of them seem to realize that Monroe is still the one with the power and responsibility, presenting a sort of gray area in which Heller is deliberately challenging her audience. It's precisely this challenge, in which we know clearly what the right thing to do for these characters is but we sympathize with her horrible choices anyway, that makes the movie great.
It begs the question: is Minnie a victim? It's ripe for debate. She is never directly portrayed as a victim, but rather a strikingly self-assured (if not entirely self-possessed) young woman. Nothing about this movie invites us to regard her as a slut, even though a couple of characters refer to her as a nympho -- a type of sex-negativity she actively resists. In spite of the ways it gets her into trouble -- something that happens to any teen regardless of gender -- it's refreshing to see a young woman portrayed as a wholly sexual being, someone merely navigating the sudden and forceful awakening of such feelings in any kid.
We always feel like we're inside the head of this 15-year-old girl -- and a multi-dimensional one, at that. Her "diary" is, conveniently, something she records with a microphone onto cassettes, making it easier to take voice-over narration. One might wonder how someone could be so stupid as to record the details of an affair she clearly wants kept secret, but it fits: teenagers do stupid things that they don't think through. Minnie is also a cartoonist, and Heller sprinkles the narrative with animations of Minnie's drawings, which are always charming, consistently bring the scenes further life and depth, and are used just sparingly enough that they never become overbearing. The paper stars in her bedroom start to twinkle. Her bathtub is suddenly surrounded by a drawn forest. Her drawings occasionally talk back to her.
The actors are solid all around, but Bel Powley is the best thing about this movie, the primary reason to see it. She exudes a rare combination of innocence and intended maturity, occupying the space between childhood and wisdom through experience. Minnie has an extended affair with Monroe, but also starts having sex with boys her age -- boys who, predictably, don't really know what they're doing sexually. But she years for experience, and thinks things we still relate to as adults. She tells one of her drawings about how badly she wants to be touched; the drawing replies, "Everyone wants to be touched." It's something this movie provides, in its own singular and curious way.