The first word in my notepad while watching The Diary of a Teenage Girl was ‘frothy’. The final phrase? ‘Sexual depravity’. It’s an understandable clash of tone and genre that at times, slightly overrules Marielle Heller’s stark directorial debut. An otherwise refreshing look at the bizarre life of a fifteen year old girl in 1970’s San Francisco, it bursts through the screen with a sort of sordid beauty, even if its protagonist is slightly premature.

Fifteen year old Minnie lives at home with her drunkard mother and her specky younger sister. It seems that most of the time, her mother’s boyfriend Monroe is around. Uncomfortably attracted to the man who is twenty years her senior, she discovers the feeling is reciprocal. Now, the pair find themselves engaged in a love affair that expands Minnie’s premature sexual scope.

Self assure from the start, The Diary of a Teenage Girl is at times a animated work of airy, teenage kook. What tends to happen to films in the teen genre is that they get trapped by their audiences; thirty-something filmmakers making films for 18 year olds with rare, slight success.

The plot follows Minnie and her best friend through their own curious encounters with sex, becoming almost a competition. It is at times rather tongue in cheek, and its often hard to differentiate these teenagers care free attitude with a concerning lack of parental attention.  Teenage Girl doesn’t really have a set audience, as its hormone-injected attitudes make way for a relationship with sexual depravity a kin to some scenes in Lars von Trier’s Nymphomaniac. Thematically, of course. The screen is never filled with an oversized phallus unless its in cartoon form.

Alexander Skarsgård and charismatic Brit sensation Bel Powley seriously steal the show here. The unlikely couple carry the film’s topsy turvy subject matter with such whip-smart ease that their performances overshadow whats going on underneath. The seldom seen nature of Kristen Wiig’s performance as Minnie’s mother is one of the major disappointments. A woman distracted by a daytime life of mundanity and late night life of excess, she’s rarely present but steals some of the film’s finest moments; for once allowing Wiig to show off her emotive acting chops.

When it comes to the way in which Minnie’s story is told, there’s a slight dilemma. It’s near impossible to line up your own perception of the film’s activity with the director’s perception. The darkest subject matter of Teenage Girl doesn’t seem formally dwelled upon. The manipulative nature of Monroe (played brilliantly by Alexander Skarsgård) seems like a mere subplot beneath intimate sex scenes; resulting in the imminent disaster that is about to occur being blamed on a young girl. In essence, Monroe is an attractive, rugged Humbert, and Minnie is a slightly obsessive version of Dolores. It is hard to ignore the fact that Skarsgård’s character is essentially a paedophile, and as things progress and the pair come dangerously close to being caught, Minnie looks hauntingly more childlike; her mental age lining up with her real life one. This takes away from the fact that, otherwise, The Diary of a Teenage Girl is a serious sexual statement perhaps disguised as a teen comedy.

The Diary of a Teenage Girl could either be a bizarre teen dramedy or a underdeveloped depiction of child molestation. Either way, it’s a riveting, provocative watch; unraveling like a confident retelling of Lolita.

★★★★☆

The Diary of a Teenage Girl has its UK Premiere at the Edinburgh International Film Festival. For ticketing information, head to the EIFF website.