This twisty thriller keeps viewers on edge, writes Michael Dwyer

Halfway through this French thriller, the teasingly intricate screenplay has introduced so many significant characters and deliberately withheld so much crucial information that the movie becomes as frustrating as a particularly difficult crossword. There remains an abundance of clues to be solved and connected - and the satisfying pleasure of filling in all the blanks as one revelation leads to another.

Now 34, director Guillaume Canet made his mark as an actor and heart-throb, best known here for his leading roles in The Beach and Joyeux Noël, and made his feature debut as a director with Mon Idole (2001). It failed to get a release here, which is our loss, given the impressive flair he demonstrates in orchestrating Tell No One in all its tantalising complexity. At this year's French film awards, the Césars, it received prizes for best director, actor (François Cluzet), music and film editing.

Its source is a novel by US crime writer Harlan Coben, artfully transposed by Canet and co-screenwriter Philippe Lefebvre from New York to Paris. Its geographic spread extends from the rundown banlieus to an immaculately maintained mansion, and across a busy motorway and through the side streets of Paris in a gripping extended chase sequence that is dexterously photographed and edited.

Everything that happens in this eventful thriller is observed through the sad eyes of a Versailles paediatrician, Alex Beck (Cluzet), who, as it begins, is blissfully married to his childhood sweetheart, Margot (Marie-Josée Croze). An idyllic night alone together turns to tragedy when she disappears; after her body is identified, the police instinctively suspect Alex, but a serial killer is charged with her brutal murder.

Eight years later, Alex is trying to get on with life, dedicating himself to his young patients but still suffering a deep sense of loss. He receives an anonymous email that jolts him, and when two bodies are found in the area of the earlier crime, he comes under suspicion again.

The jigsaw that emerges from the movie's premise introduces diverse characters whose fates are interlinked, and played by some of the cream of French cinema. They include Alex's showjumper sister (Marina Hands) and her lesbian lover (Kristin Scott- Thomas); Margot's gruff father,

a retired police officer (André Dussollier); Alex's coolly determined lawyer (Nathalie Baye); the detectives (François Berléand and co-writer Lefebvre) obsessed with their investigation; a resourceful fixer (Gilles Lellouche) who appreciates Alex's care for his son; and an elderly millionaire (Jean Rochefort exuding hauteur) and his son, played by Canet himself as the most unsympathetic character in the sinister story.

Cluzet, who resembles Dustin Hoffman in his mid-to-late 40s,

is the anchor, expressively capturing Alex's inner turmoil

as he struggles to unravel the mystery to which he is pivotal. Reflecting his plight, the improvised guitar-driven original score by M (Mathieu Chedid) subtly turns from melancholy to urgent as dark deeds are played out against brilliant sunshine.

Canet's stylish thriller turns unexpectedly conventional in

its denouement, which is explicatory in the manner of the final revelation in an Agatha Christie tale, but quite appropriate as it demands that viewers stay alert to the end.