World War I gets a glossy, sepia-tinted makeover in Jean-Pierre Jeunet's relentlessly whimsical "A Very Long Engagement". Jeunet's trademark style consists of mechanical, almost clockwork-like narrative construction garnished with lavish, chocolate box production values and seasoned with faux-naive humour. It's an approach that worked pretty well with his previous picture, the romantic fantasy "Amelie", thanks in no small part to the inimitable contribution of Audrey Tatou in the title role. Applied to vastly more sombre material, Jeunet's method backfires rather badly.

Tatou crops up again here in a variation on the same sort of sweetly off-beat character as Amelie. She's Mathilde, an orphan who lives quietly with her aunt and uncle in an idyllic rural setting, determined to trace what became of her child sweetheart Manech (Gaspard Ulliel), several years after he went missing in the War. Manech was one of five soldiers court-martialled for self-mutilation in 1917 at 'Bingo Crepuscule', and sent over the top into no-man's-land as a punishment. He's presumed dead by all but Mathilde who cherishes the hope of finding him. The film follows Mathilde's dogged quest to find out what really happened, and as she delves deeper she uncovers a sad, even shocking story of high-ranking corruption and inhumanity. Mathilde must filter the facts from the fictions that arise from various conflicting, overlapping or incomplete accounts of what seem to be Manech's final hours.

All this should be poignant and gripping, but it's more often simply confusing thanks to the visual and verbal clutter with which Jeunet pummels his audience. There's simply too much going on at any one time, including an intrusive narration that adds precisely nothing to our appreciation of the story and characters. Without a moment's respite from informational overload, I felt denied the space to reflect on Mathilde's quest or the room to engage with it on my own terms. Jeunet's unceasingly busy camera spirals and swoops and circles, caressing every surface contour of his exquisitely designed production, but it singularly fails to penetrate to the soul beneath the story's skin. The result is deeply uninvolving, and worse, grotesque. The First World War was a particularly dark hour in human history. Imagine it re-created as one of those picturesque commercials for a well known Belgian lager, and you have the measure of this film.