In Geneva, young student-cum-model Valentine (Irene Jacob) runs over a dog in the street and in taking it back to its owner, finds the cantankerous Jean-Louis Trintignant listening in on his neighbours' phone-calls.

"What were you?" she asks. "A cop?"

"Worse. A judge."

Red is about the burgeoning friendship between the improbable couple and the gradual realisation that, but for 40 years, they would have been lovers. Against this, the script (by Kieslowski and long-time collaborator Krzysztof Piesiewicz) juxtaposes the break-up of a relationship between a young law student (Jean-Pierre Lorit) and his girlfriend (Frederique Feder).

Red is a film of opposites, of fate and coincidence, cynicism and faith, communication and listening. In a very un-Kieslowski moment, it opens tracking a call down undersea cables to its unanswered end. Thereafter the telephone is a recurring image: the judge's spying; Valentine to her lover Michel in England; Auguste ringing his girlfriend's weather service just to speak to her. And yet seldom is there communication - witness Michel's mounting, irrational jealousy, or given the short distance between their apartments, Valentine and Auguste's unawareness of one another.

Red is more schematic than any of Kieslowski's other films but never manipulative. At the beginning there is a sense of disjointed narrative, built-up of small coincidences, but the screenplay resolves these apparently dissolute elements with a cohesion and finality worthy of the director's best work.

The picture's core, as Jacob explains, belongs not to her or Trintignant but both; and these are magnificent performances. The formidable Jacob (1991 Cannes winner for the luminous The Double Life of Veronique) is exceptional, conveying more in a single glance than most of her contemporaries command from an entire performance. French veteran Trintignant gives a career-best showing.

Technically this is the most fluent of this exceptional director's films. Piotr Sobocinski's cinematography is both fluid and sharp. It's perhaps ironic that the most outstanding moments are quiet ones: Jacob's face lit by a naked bulb; the way she quietly plays with the wire on a set of headphones. Zbigniew Presiner's score (with help from mythical regular Van Den Budenmayer) is an unqualified triumph.

As the final part of the Three Colours trilogy, it falls to Red to make sense of the series, and the startling (ironic?) coda - which restores the principals from Blue and White - seems both playful in its identifying director and judge, and, in the final, ambiguous image, utterly overwhelming.

Eighteen months or so back Kieslowski announced his intention to retire. By Cannes last May - where the film premiered - he was adamant. As history will show, the festival's Palme D'Or went to Quentin Tarantino's entertaining but flatulent and emotionally hollow Pulp Fiction, leaving the Pole to go home with nothing. One suspects that he wouldn't really mind. (Besides which, Red has since taken two major US critics awards.) He leaves behind an exceptional body of work that will stimulate and entrance audiences long after the crash and bang of Tarantino has become but a distant memory.