French director Bertrand Mandico turns the arthouse weirdness dial up to 11 with his erotically uninhibited and deeply bizarre feature debut set at the turn of the last century. Some might find the movie outrageously self-indulgent, but I was drawn into its hermetically sealed world of oddness – and Mandico pays attention to character to a degree that experimental film-makers often don’t bother with.

Anaël Snoek is cruel, swaggering Tanguy, a teenage boy who looks like a cross between a young Tilda Swinton and Draco Malfoy. At boarding school, Tanguy is a junior member of a gang of delinquents, the entitled sons and heirs of the rich elite. One night, the boys rape a female teacher while gripped by a collective rage they call Trevor (perhaps that doesn’t sound so daft in French. It reminded me of The League of Gentleman’s Papa Lazarou calling everyone Dave).

As punishment, the five are packed off to be “re-educated” by a grizzled Dutch sailor called The Captain, who has a track record for taming wild boys. (He also has the coordinates of his favourite island tattooed on his penis.) The gang’s final destination is a lush super-fertile paradise island, where they feast on indecently phallic fruit that causes a sexual metamorphosis, transforming them from male to female.

It is a spoiler to mention here that the boys are played by female actors? It’s fairly obvious from a quick glance at IMDb or the credits – and the fact adds shades of complexity to what might otherwise be a toxic, highly stylised portrayal of rape. The casting has led to claims that the film has something meaningful to say about biological determinism and gender. I’m not so sure, and I found its erotic streak borderline juvenile in places. Still, Mandico has made a wildly strange debut, striking enough to make you sit up and pay attention.