The presence of stars from Michael Haneke’s “The Piano Teacher” and Bernardo Bertolucci’s “The Dreamers,” two of the most sexually explicit films of recent years, may serve as due warning to the easily offended–and even the not so easily offended–that “Ma Mere” isn’t for them. In Christophe Honore’s picture, based on a novel by Georges Bataille, Isabelle Huppert plays Helene, a self-proclaimed champion hedonist, who introduces her Catholic-school trained son Pierre (Louis Garrel) to the most provocative modes of sexual pleasure, or to use language that might be more accurate, to the depths of depravity–which include not merely random intercourse and sado-masochism, but incest as well. The boy seems initially ambivalent, but mother’s plans bear fruit, and in a paroxysm of lust and defilement at the close, one of the two winds up dead and the other totally debased–-all to the strains of the song “Happy Together” by the Turtles. (Common decency precludes too graphic a description of how this all comes about. Rest assured that the film is quite graphic enough.)

The point of all this isn’t terribly clear. Certainly “Ma Mere” can’t be taken as a simply realistic depiction of the human inclination to perversity–the utterly surrealistic portrait it draws of the Canary Islands night scene, in which the story is set, as a sort of degenerate’s paradise is evidence enough of that–but whatever the intent, the film’s heightened atmosphere doesn’t give its tale of extreme family dysfunction any deeper meaning. Is it meant to serve as some sort of demonstration that nature trumps nurture? That a strict upbringing and pietistic education can’t overcome an innate drive to indulge in the most socially unacceptable behavior? Or–to speak in Freudian terms–that every person has a sexual desire for the parent of the opposite sex? That conventional morality is something that must be overcome to live fully? Or that freedom is all that matters? Or that sex and death (or pain) are one and the same? Whatever Honore’s intention (or Bataille’s) in this respect, the film certainly doesn’t succeed in rising above its rather sick surface. It wallows in repellant imagery rather than enlightening us intellectually in any serious way, and it offers no real psychological insight into the characters, who are unintelligible symbols than rounded human beings. It certainly manages to be unsettling, but also increasingly preposterous, incoherent and unpleasant.

Still, one has to give the cast credit–if not for excellence, at least for courage. Philippe Duclos has a poignant cameo as Pierre’s father (although his character earns our detestation for a scene in which the boy opens his safe); Joana Preiss has a suitably vampire-like look as Helene’s partner in loose conduct; Emma de Caunes manages the air of feigned innocence necessary for Hansi, the girl Helene hires to introduce her son to some unusual activities in her absence; and Jean-Baptiste Montagut shows himself willing to accept every sort of humiliation as Hansi’s strangely submissive friend Loulou. (One’s tempted to say the whole film is a lulu.) But certainly Huppert and Garrel deserve the lion’s share of attention. It would be difficult to imagine more uninhibited actors. She uses her clipped, vaguely distracted air to create a memorable portrait of a monstrously libertine woman, even though even she can’t reveal an inner life where none appears to exist. In a way young Garrel is even more extraordinary. He shows not the slightest trace of embarrassment engaging in front of the filmmaking crew–and us–in acts that most people would be flustered to perform in deepest solitude. Unfortunately, like Huppert’s Helene, his Pierre is a cipher, a blank slate of inexplicable drives and unspoken desires. They make these unholy figures morbidly fascinating, but over time watching them seems akin to gawking at the victims of a traffic accident; and the fact that it’s an accident they chose to participate in makes the whole thing even more unpalatable.

It goes without saying that “Ma Mere” is not a film that will appeal to many people. The problem is that Honore and his cast are unable to persuade us that it should appeal to anyone at all.