Dir: Olivier Assayas. France 2002. 129mins. Screened in Competition

Demonlover is the latest victim of the French tradition whereby a highly respected director over-reaches drastically, eliciting critical calumny and press-show booing - something that has happened in Cannes to the likes of Beineix, Carax and Kassovitz. It is a shame to see it happen to Olivier Assayas, one of France's most cerebral and cine-literate directors. His latest film, which could not be further from his sedate costume drama Les Destinees Sentimentales, is undoubtedly his most experimental yet - a polished, brassy cyberthriller that for the first hour dazzles with its bold conception, but then heads into impenetrable erotic-thriller territory. Damned by its hybrid conception, it seems likely to be rejected by both ends of its possible audience: mainstream viewers will reject it as pretentious while Assayas's art-house following may find it just plain tacky. Its luridly hip pop-culture trimmings and erotic content may find a cult audience, but Demonlover's incoherence will severely limit box-office prospects.

The film establishes a tone of high-gloss elegance from the start, with a sequence set on a deluxe business flight from Tokyo to Paris. Diane (Connie Nielsen), personal assistant to corporation head Volf (Jean-Baptiste Malartre) spikes the drink of older colleague Karen (Dominique Reymond) who on arrival finds herself kidnapped. Diane conveniently finds herself doing Karen's job, working alongside sharkish exec Herve (Charles Berling) on an important Japanese deal. Volf's company is buying into Tokyo Anime, a company specialising in animated sci-porn and developing a revolutionary new 3D technique. Volf wants to clinch a deal with US hot-shots Demonlover, an internet company out to dominate the anime market and crush rival Mangatronics - for whom Diane moonlights as a secret operative. Things take a nasty turn when Demonlover rep Elaine (Gian Gershon) arrives from the States; casing her room, Diane ends up killing her. In deep water, Diane has also incurred the enmity of secretary Elise (Chloe Sevigny), who has a dark agenda of her own. And then there is the murky matter of Demonlover's porn connections, especially interactive torture site Hell Fire Club, of which Diane falls foul.

Demonlover starts promisingly as a hi-tech industrial-espionage thriller that seems to have the pulse of a self-consciously glossy international business world. Assayas brilliantly evokes the mood of cagey business lunches, impersonal hotels, thrill-seeking bored executives; one of France's most cosmopolitan directors, Assayas also seems very au fait with the ins and outs of the anime world. The first hour, shuttling between Paris and Tokyo, is an energetic, hyper-polished affair, with a seductive sense of East-West cool, marking Assayas as nothing if not confident in his chosen new territory of cutting-edge stylishness.

But things take a disastrous turn when Diane does an improbable cat-burglar act - apparently a knowing nod to Assayas's earlier Irma Vep. The scene quickly turns into a protracted bloody fight - a dash of Hitchcock or perhaps DePalma' - before Diane blacks out, waking to find all traces of the struggle mysteriously cleaned up. As the plot thickens, different characters seem to pull the strings at different times, manipulating each other with the callousness of internet punters torturing their fantasy on-screen victims. The film enters that familiar zone of existential ambiguity that David Cronenberg mapped out in both Videodrome and eXistenZ, apparent references here, but that Assayas is unable to convincingly control. The ever-more hysterical narrative leads up to a bewildering car-chase climax, and a coda that, although undoubtedly clever, leaves a very nasty taste in the mouth.

Assayas has some serious points to make here about the marketing and ownership of images, and the dangers, as well as the thrills, of new computer technologies, especially when allied to pornography. Taking a thematic cue from American novelist Don De Lillo, Demonlover is Assayas's statement about the postmodern global condition, and recalls Wim Wenders's The End of Violence as a case of an art-house auteur critiquing pop culture through its own language. But Assayas is dangerously compromised by his own fascination with glamour, bombarding us with out-and-out trendiness - not least in the casting of indie-queen Sevigny, and in the use of highbrow US rockers Sonic Youth to provide a soundtrack running from abrasive thrash to ominous ambient throbbing.

The film really comes unstuck in its exploration of computer sex world, bombarding the screen with intense digital evocations of the borderline-snuff Hell Fire Club site, where punters can watch the torture of fantasy heroines from Wonder Woman to Lara Croft, played by living victims. Nielsen is an unsatisfying lead, cold and unreadable with an impassive, high-pitched French delivery that sounds as if it could be dubbed by Jane Birkin. Conversely, Sevigny is impressively abrasive, Reymond commandingly ambivalent, and Berling, brutish and shaven-headed, playing it tougher and nastier than he has previously. Gershon is on screen too briefly, enlivening matters enormously as a glamorous, catty operator.

Visually, Assayas enters audacious new territory, not just in Charlotte Bayle's extravagant computer graphics, but in the range of looks provided by cinematographer Denis Lenoir, ranging from sheened steel-and-glass tones to hyper-grainy night photography that appears to have been further retouched digitally. To his credit, Assayas is out there on the cutting edge of cinema language, but once he's there, is unsure how to keep his audience there with him. Either he aspires to be France's David Fincher, or he has taken a severe over-dose of trendy pills. And admirers of the pithier, more economical Irma Vep must be wondering, what's Assayas's thing with rubber catsuits'

Prod co: Elizabeth Films
Fr dist: SND
Int'l sale: Wild Bunch
Scr: Olivier Assayas
Cinematography: Denis Lenoir
Ed: Luc Barnier
Prod des: Francois-Renaud Labarthe
Main cast: Connie Nielsen, Charles Berling, Chloe Sevigny, Gina Gershon, Dominique Reymond, Jean-Baptiste Malartre