Disturbing, repulsive, and compelling, Ma Mère is a fierce confrontation of the most difficult of taboos. Adapted from Georges Bataille's controversial 60s novel, it's the story of the teenage Pierre, who, after the death of his distant father, is pulled cataclysmically into the sexual orbit of his tearaway mother Helène (Isabelle Huppert). Pushing each other to ever worse depths among the dreary sex-tourists of Gran Canaria, mother and son spiral towards torturous self-annihilation.

As the obsessed Pierre, Louis Garrel (The Dreamers) can posture existentially with the best of them, but lines like "her ass makes me understand that I never really loved God" stretch credulity a tad. Sexual shock-cinema like this walks a tricky line; without the intellectual nous to back it up, it can appear simply an exercise in cinematic chicken - relentlessly daring the audience to flinch first.

"SIMPLY TOO ALIEN TO COMPREHEND"

Boldly leading a grand tour of all the depravities it can capture in close-up - masturbation, cross-generational orgies, urination, coprophilia (if you don't know, don't ask), voyeurism, sadism, incest, necrophilia - Ma Mère only remains plausible when it keeps the psychological pitch higher than the physical one. Despite an eye-watering performance from Huppert and sparkling support from Emma (daughter of Antoine) de Caunes, this balance, unfortunately, proves unsustainable. The philosophising feels bolted on and the motivations of all the characters soon become simply too alien to comprehend.

Yet despite its failings, this is powerful, uncompromising cinema that makes wholehearted attempts at new things and almost, almost pulls them off. Just don't watch with mother.

In French with English subtitles.