In Amélie , French director Jean-Pierre Jeunet looked at love through the eyes of Audrey Tautou's ingénue waitress. In A Very Long Engagement Audrey's more mature eyes look for it again - this time in the mud and blood of World War I. In 1917 five French soldiers found guilty of self-mutilation are sentenced to death and sent unarmed into no-man's land. Mathilde's (Tautou) fiancé Manek (Gaspard Ulliel) is one of them. Believing he's still alive, Mathilde wilfully hopes against hope and searches for the truth. Fans of director Jeunet will know what to expect next - a labyrinthine tall tale shot through with bittersweet asides, black humour and ravishing photography. And they won't be disappointed.

It takes someone of Jeunet's vision and verve to pull off a romantic comedy cum mystery alongside gritty scenes of trench warfare. But telling its tale in a spiralling swirl of vignettes, Engagement isn't easy to follow. The cast of characters weave in and out, asking us to écoutez and répétez their names, as we'll need them later on. The film bounds us along like the shaggy-dog that it is and we're soon hungry for the treats that Jeunet tosses our way. Chief of which is Tautou's Mathilde - the eternally optimistic but vulnerable woman, lamed by polio. Given to flights of fancy, clutching at superstitious fate-tempting, Mathilde is still a sassy lass, doggedly following up leads and solving riddles. There are cameos aplenty too - Jeunet favourite Dominique Pinon ( Delicatessen, City of Lost Children, Amélie) as her supportive guardian and Jeunet fan Jodie Foster who asked for the part and displays her fluent French in an affecting side-story. And there are trademark black touches - a zeppelin hovers inside a bomb-blasted hospital and why is a mysterious lady of the night killing off top French officers? All will be revealed. Indeed, with Jeunet's blink-and-you'll-miss-it approach every detail counts. Loose ends will be tied - and there should be prizes for those who can explain them all afterwards.

Thanks to Amélie's cinematographer Bruno Delbonnel, everything looks wonderful - the chocolate box countryside, the sepia of 1920s Paris, even the chilling aerial sweeps of the trenches. The battle-scenes are unflinching and well-created. And there are touching moments - the childhood meeting of Mathilde and Manek stands out - amid the tricksy plotting.

Ultimately though, like Mathilde, Jeunet is an optimist and A Very Long Engagement has a cheeky lightness of tone that keeps us entertained but somehow seems at odds with Mathilde's - and our - emotional journey. For all its artfulness, A Very Long Engagement is powered by the simple hope of its heroine. And whatever you think of Jeunet's filmmaking, like Mathilde, you'll be aching to know whether her man is alive.

Glenn Watson 23/01/05