4 stars

It doesn't quite capture its original French title, L'Evenement meaning "the event", but if the name this new film is known by in English has a vaguely inconsequential air to it, a note of caution. This is about a young woman, a student still in her teens, who becomes pregnant and seeks an abortion at a time when the procedure was illegal and highly controversial.

Happening is based on the book of the same name by Annie Ernaux, a prolific French author who has used the events of her own life for inspiration, including an abortion in 1963. Anne Duchesne, as Ernaux was known at that time, is the main character here. She is played by Anamaria Vartolomei in a performance of rare depth.

In the intimate opening moments, Anne is one of three young students at college together, as inseparable as friends are at that age as they prep for university and adult life. As they get ready together for a night out at the club, they are more a unit than individuals, as besties are at that age, sharing gum and comparing bra sizes.

Their education in the classics, conjugating Latin verbs and making impassioned comparisons between the French literary giants, lends a rarefied contrast to the sexual awakening going on, but it is true to the times. Communications studies were still below the horizon.

From the beginning, the atmosphere director Audrey Diwan creates is one of the excitement and anticipation of late adolescence, a time of experimentation and risk, when the allure of the unknown is fraught with danger. When Anne finds that she is pregnant, it is a secret that she doesn't even confide to her girlfriends, Helene (Luana Bajrami) and Brigitte (Louise Orry-Diquero), for reasons that become clear.

Director Diwan, also one of the writers, has a wonderful flair for creating the private world of teenage girls. There's a conspiratorial, febrile atmosphere as they share views on the young men they dance and drink with at the club. While they exchange confidences, they are tumbling into private experiences their own.

Suddenly, a visit to the doctor confirms that Anne is pregnant. "Do something," she exclaims. "You can't ask me that," he responds in one of the less confronting of exchanges that she has when she insists on some help.

During this crucible moment, she must also decide what she wants to do with her life. The prospect of studying literature at university will take precedence. She is certain she doesn't want to be a mother yet, and becomes increasingly desperate as the possibilities for an intervention close down. Trying to induce a miscarriage with a knitting needle is one of several scenes that will disturb and shock, but the graphic content can be justified in the context.

While abortion was opposed by many doctors and illegal in conservative France in 1963, there were few options open for a young woman like Anne.

There was the hypocrisy of others to deal with. Anne is hit on by a male acquaintance because she was pregnant anyway, she is spurned by her fellow students in the dormitory for some aberrant behaviour, and she is unable to ask friends or family for assistance. At this time in her life Anne is an isolated figure.

Trips home to see her mother, Gabrielle (Sandrine Bonnaire), and father (Eric Verdin) provide some solace. There is a lovely, simple encounter around the radio while gathered at the kitchen table. Her parents share a laugh while their daughter looks on, smiling. It's one of many delicate moments of authenticity in Happening, winner of the Golden Lion for best film at the Venice Film Festival last year.

Equally, the film is unsparing as the camera follows Anne around, perched on her shoulder during a procedure, always intent on conveying her perspective. Among the final scenes, there is a single shot that produced a collective gasp in the cinema when I saw it. Confronting, but as always true to the moment.

From girls' nights out to the music of Buddy Holly and other early rock and rollers, to the incidental, urgent compositions in its latter stages, this drama is about a quest for freedom in the narrow and the broader sense. It is really impressive.