It's 1976 San Francisco. Fifteen year old Minnie Goetze (Bel Powley) is overjoyed at losing her virginity to her mother Charlotte (Kristen Wiig)'s boyfriend Monroe (Alexander Skarsgård). They begin a secret affair. Minnie and her friend Kimmie Minter get into various adult situations. Her stepfather Pascal MacCorkill (Christopher Meloni) wants to stay in her and her sister Gretel's lives. She records tapes of her diary and draws inspired by cartoonist Aline Kominsky.

This takes a less conventional look at the sexual coming-of-age story from the female perspective. It is not flowers and puppies. It is highly sexual in nature. It is unflinching. My main problem is that Bel is a little too old to play the fifteen year old. I rather have a younger actress do the role without the nudity. There is a shock with a man having sex with a young girl that is missing in this movie. She looks 20s. I'm reminded of Heather Matarazzo in 'Welcome to the Dollhouse' and the shock of that sexual subject matter. This movie has the same shocking subject.

The Diary of a Teenage Girl could easily be one of these kookie offbeat coming of age films. Instead It decides to be more daring and frank instead.

Minnie Goetze (Bel Powley) is a 15 year old teenager who has sex with her bohemian mother's Charlotte (Kristen Wiig) boyfriend Monroe (Alexander Skarsgard) and enjoys the experience. In fact she likes sex, wants more of it and experiments with her friend Kimmie as they both deals with their raging hormones.

Minnie keep a diary on tape of her sexual exploits which is probably not wise when her mother becomes suspicious. The film uses cartoons to display some of Minnie's frank thoughts.

Director Marielle Heller sets the film in San Francisco of 1976. The period is very evocative and is set during the trial of Patty Hearst which the characters comment on. It allows the film to get away from the fact that Monroe is breaking the law by sleeping with an undersage girl by protraying it as a different era back then.

The film makes no moral judgment about an older guy having sex with a minor, although Monroe's relationship is in a non predatory way. It is probably more refreshing that a film about a teenage girl having sex avoids many of the usual tropes.

It is a bravura performance by British actress Bel Powey but she is too old to play a 15 year old and looks it. I did find the film hollow somewhat but maybe this was something Minnie eventually released. Sex was fun but eventually it meant nothing.

My, how times have changed. Here is fifteen year old high school student, Bel Powley, coming of age in 1970s San Francisco. It's La Dolce Vita, according to this movie. I mean, sex, drugs, rock and roll. Powley's mother, Kristen Wiig, has a handsome young boyfriend, Alexander Skarsgård. Powley teases him and finally seduces him, and they get it on until Mom finds out about the affair. There are a few minutes given over to deep loneliness and despair. Powley almost is entrapped in a heroin joint by a lesbian but pulls herself away in the nick of time, as they say, and finally returns to Mom at home.

Throughout these incidents -- involving not just Skarsgard but a handsome class mate and two men who pay for BJs in a toilet -- Powley has nothing on her mind but sex. Not marriage and a home. Not yet. Her values are entirely organoleptic. She is obsessed with being touched and banged. The F bomb is liberally distributed throughout the story. This is very much different from my own childhood years in a working-class suburb of Newark, New Jersey, a generation or so earlier. It was easy to coast through Hillside High School without ever discovering what a female breast felt like. Where were the Bel Powley's when we needed them, hey? O tempora, or mores! It isn't a Lifetime Movie though, not a soap opera, and it can hardly be called a domestic drama. The device of having Powley narrate the story into a tape recorder is a bit of a cliché but that's okay. It helps link the episodes together and Powley reads well enough. She's cast nearly perfectly. Not very pretty but not quite homely either, and shapeless rather than chubby. Her voice has an endearing crack when she tries to shout. The character is at that break point in the life course, a liminal state in which one enters adulthood without quite having outgrown childhood. For kicks, Powley and her girl friend jump up and down on the bed and sing songs. Between BJs, that is.

But then all the performances are better than might be expected. As the uncertain mother on the hedonic treadmill, Krisen Wiig registers as savvy. As the seduced, Skarsgard ought to know better. Powley is fifteen. Groucho Marx used to refer to girls that age as San Quentin Quail, and Errol Flynn wound up in a scandalous affair leading to his trial as a rapist for doing what Skarsgars does to Powley. Except, of course, with Flynn being what he was, there were two teenage girls, not one.

Yet this isn't a trite movie, with Skarsgard as the Humbert Humbert of the piece. Skarsgard's character is impulsive but has adult sensibilities and is generous with his compassion. He gives a fine, thoughtful performance. The direction too is whimsical but very engaging. There are episodes that are done as cartoons resembling Crumb's. The camera doesn't wobble. The cuts don't take place until the heft of the scene is absorbed by the viewer.

The city is a scenic place, a tourist mecca, but it isn't milked for its glamor. And its atmosphere is nicely captured by the director, Marielle Heller. I was living there at the time this story takes place and loved its go-to-hell raffishness. Pot plants grew in the windows. Somebody was running for mayor -- a garishly made-up transvestite dressed in a nun's habit but with a tiny skirt and fishnet stockings. Name on the ballot: Sister Boom Boom.