The last road movie I watched at a film festival was Y Tu Mama Tambien, a joyous celebration of life, vigour, and sexual vitality amidst the spectre of death. Twentynine Palms could be the anti-Mama, with the lead couple, David and Katia driving through Joshua Tree National Park, a landscape where life has been baked out. David and Katia are embarking on a trip ostensibly to look for scouting locations, but ultimately they're cruising down a lost highway, plunging further downward into the loss of language and ultimately the loss of sanity.

When does language collapse? At some point - sex, extreme violence - instincts take over, director Bruno Dumont seems to be saying, and we are reduced to animalistic grunting. The only intelligible speech is blurred into the background, and in any case are the rants of police officers on petty quarrels and talk show guests. Conversations between David, who's American, and Katia, his French girlfriend, are necessarily tangential, the former primarily speaking English and the latter primarily French. And without any communication, everything looks loveless in this movie: the sex is acrobatic but holds the hint of menace, with the wild screams remniscent of animals in heat rather than partners in love.

That combination of menace and emptiness is echoed everywhere. The sex scenes in the swimming pool reminded one of the use of pools as a visual metaphor for death or emptiness: Dustin Hoffman's swim in The Graduate, the 'murder mystery' in Swimming Pool, David Hockney paintings. In the one part of the movie I found truly compelling, the couple fights on the street and in back alleys, amid a dense atmosphere of dim lighting and heavy breathing.

So Dumont takes the link between sex and death (la petit mort) and inverts it, subjecting us to a view of sex in the harshest light and landscape possible, giving us a climax of irrational, insane violence (this ending was much like the ending to Fat Girl, which ends in a random act of atrocity). But I left the theatre underwhelmed: ultimately, Twentynine Palms comes across a sort of set-piece, with the elements seemingly arranged just for the sake of demonstrating inhumanity. It's a blistering assault on one's senses, but at no time did I feel it pierced through into my sensibility.