Confidences trop intimes (15)

The French director Patrice Leconte likes to study the drama of the human face, probing the secrets tucked within its contours and creases. His last film L'Homme du train didn't make a great deal of sense but got away with it by attending closely to the great Gallic physiognomies of Jean Rochefort and Johnny Hallyday; their histories embroidered in eloquent crow's feet and melancholy eyes. His latest, Confidences trop intimes, is another two-hander, and while the characters' faces are somewhat younger, they too are scrutinised by Leconte's camera as if beneath a kind of spiritual X-ray. What do these people mean to one another? It is a mark of the film's atmosphere of civilised intrigue that we are kept guessing to the very last.

Part of the pleasure resides in not quite knowing what sort of film it's meant to be. At first, one senses the shade of Hitchcock in its faintly cruel sport with mistaken identity. A young woman, Anna (Sandrine Bonnaire), turns up at a therapist's office without an appointment and proceeds to confess the living hell of her marriage to William (Fabrice Luchini), who listens with eager concern. Nothing remarkable here except that Anna went through the wrong door - William, it transpires, isn't a therapist at all but a tax adviser, and the couch in his office was just for show. "You cheated me," she says accusingly when the imposture comes to light, and it's true that William didn't quite get round to telling his confidant that she was in the wrong office. When he later telephones her, the number she has given him turns out to be the automated weather report.

Their accidental encounter thrums with possibility. Anna is clearly not all she seems, so we could be heading towards the sinister fortuity of Robert Walker and Farley Granger meeting as Strangers on a Train, or else her confessions of sexual frustration are intended to find an answering fire in William's loins.

What makes it difficult to decide is Luchini's confoundingly ambiguous pres- ence at the film's centre: could be he's a romantic hero in waiting, but his anxious eyes and shifty manner hint that he's just a creep who can't believe his luck. He doesn't seem altogether sure himself, and by a nice irony ends up in the office of Dr Monnier (Michel Duchaussoy) along the corridor, the therapist whom Anna first intended to consult.

A worldly, unsurprisable man, Monnier assures William that tax advice and psychotherapy aren't so very different ("We both treat the same neuroses - what to hide, what to reveal") and that Anna's appeal for help may not have been misdirected after all - "People have lost the art of listening." The doctor encourages William to take a more philosophical view of his new "client", though he's not so philosophical himself that he omits to charge him €120 for their little confab.

Perhaps William is a good listener, because Anna returns, despite feeling taken in during their first meeting. They begin to have regular appointments, to the chagrin of his matronly secretary Mrs Mulon (Hélène Surgere) and the bemusement of William's ex, Jeanne (Anne Brochet). The strange thing is that, though Anna does most of the talking, it's William whose character is gradually uncovered. At first he seems your average uptight professional drone, with his neatly knotted ties and an office whose immaculate surfaces he dusts himself.

But Anna gets behind his defences, winkling out information that makes her interlocutor suddenly appear more complex: his office, for instance, used to be his father's, and leads on to a bedroom where his parents used to sleep - he keeps it locked. The vintage toys ranged across his sideboard suggest both a collector's ardour and perhaps a deeper and more troubled attachment to his past than he cares to admit.

That William might be a weird cove becomes a distinct possibility when we see him gazing from his window into the apartments opposite - Hitchcock again - but one comes to discern in Luchini's inquiring gaze a spirit of romantic excitement rather than lonely voyeurism (the subject of Leconte's 1989 movie Monsieur Hire).

"You're not the type I imagined her with," Anna's husband says, suspecting himself cuckolded, and we can see that William is rather tickled by the suspicion, even if it is wrong. After all, who could fail to be enthralled by the prospect of Sandrine Bonnaire turning up at your place every week for an intimate chat? Bonnaire is an amazing (and sadly underseen) actress, blessed with what David Thomson has called "one of the great watching, waiting, listening, attending faces" - a gift to the steady concentration of Leconte's lens. Her transformation from the pinched, "tragic" heroine of the early scenes to the gorgeous, passive flirt echoes the film's shift from gloom to light.

Confidences trop intimes is a bewitching and often very droll affair, crisply written by Jerôme Tonnerre and nicely lit by Eduardo Serra. Leconte controls the mood with masterly assurance, keeping revelation just out of reach: is the fake shrink merely entertaining a fake neurotic, or have these people made a genuine connection?

The mystery occasionally tips too far, such as the sequence in which William trails Anna to a railway station and watches her inexplicably faint on the platform: "Some things escape you", says the wily old doctor, and some vital detail seems to have escaped the editor here. No matter - this muted duet may well prove one of the more enduring pleasures of this year.