Alexander Skarsgard (pic by Nick Step) [CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons

Alexander Skarsgård (pic by Nick Step) [CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons

As pre-teen back in the early 70s I used to kiss the posters of toothsome pop stars Donny Osmond and David Cassidy, which adorned the walls of my bedroom. Minnie, the 15-year-old heroine of The Diary of a Teenage Girl, has a less wholesome way of worshipping the Iggy Pop poster that hangs above her bed. Let’s just say that it involves something a good deal more lewd than a quick peck on the cheek .

Adapted and directed by Marielle Heller from the ‘hybrid’ novel The Diary of a Teenage Girl: An Account in Words and Pictures by Phoebe Gloeckner, the movie takes us inside the mind and the bedroom of a bright, creative and sexually curious teenage girl, growing up in San Francisco in 1976. Bel Powley, who plays Minnie, is fearless and fantastic as the elder daughter of the rather chaotic Charlotte (played by Kristen Wiig).

As the film begins, Minnie is confessing to her diary that she’s just been deflowered by her mother’s studly boyfriend Monroe (Alexander Skarsgård sporting a creepy 70s pornstache). There’s an elegantly composed flashback to the aftermath of this earth-shattering event, which Minnie captures on a polaroid so that she can study her own face for clues.

As this illicit affair progresses, Minnie discovers that far from being a passive schoolgirl she’s a sexually confident young woman, with all the dangers that entails. A pool-house tryst, drugs, a threesome, and a disastrous hook-up with Tabatha (Margarita Levieva) are all recounted with candour and varying degrees of explicitness. Meanwhile, her mum has lost her job and is beginning to suspect that Monroe’s interest in her daughter is not that of a surrogate father.

The reviews I’ve seen of The Diary of a Teenage Girl have praised its frankness and authenticity, arguing that it helps to redress the balance of years of crude American Pie-style comedies about horny teenage boys. The BBFC obviously found its depiction of burgeoning female sexuality way too dangerous, slapping the film with an unhelpful 18-certificate. (They’d probably have been much happier if Minnie had just run around San Francisco shooting people, like a female Clint Eastwood.)

Some of the most explicit sexual images in The Diary of a Teenage Girl are the beautifully rendered animated sequences that punctuate our diarist’s daydreams. Minnie is a talented cartoonist, who envisions herself as an Amazonian figure striding about the streets of the city or an iridescent half-woman/half-bird, hovering over her bedroom. Even more more visually arresting are the moments when she submerges herself in the bath, dark hair slowly pooling around head, trying to make sense of her newly unfettered libido.

The animated flowers and stars that fill the screen are like those doodles classmates would draw on the covers of their exercise books during particularly boring lessons. I hate to say this, but I was often bored and unengaged during The Diary of a Teenage Girl. I’ve seen three-and-a-half-hour Jacques Rivette films that held my attention more than this film did.

Bel Powley, who is a Londoner, brings all the pouting intensity and intelligence of the young Christina Ricci to her role as the mixed-up, longing-to-be-loved Minnie. Skarsgård and Wiig offer good support as the hedonistic couple, with limited parenting skills. But the danger of having one protagonist’s point of view is that the other characters can feel rather thinly drawn. The combative, on/off friendship between childhood friends Anna Friel and Michelle Williams in Me Without You was explored in much more depth than any of the relationships here. The script of The Diary of a Teenage Girl lacks the zinging one-liners that made Juno so enjoyable. (Perhaps we could have done with a cameo from J.K. Simmons here.)

Despite the visual flourishes of the animation I found the cinematography here flat and grainy, with every shot apparently wreathed in smog or the carelessly exhaled smoke from a joint. I’m not expecting blue skies in every scene, but did it have to look quite so dull?

The Diary of a Teenage Girl isn’t a product of the Marvel Universe, which is something to be grateful for during another intellectually bankrupt summer of brainless blockbusters. It’s well-acted and well-intentioned and likely to boost the career of its star, Bel Powley. Perhaps I’m just too far beyond my teenage years to really get it.