Jean-Pierre Jeunet's new film "A Very Long Engagement," from Sebastien Japrisot's novel of love and the First World War, tells two stories built around one moment in time. In 1917, in the Somme battlefield, five French soldiers in the trenches are convicted of self-mutilation (each one shoots a bullet through his right hand) in order to be released from service in this dread war. Their punishment is death, and a particularly cruel death: they are put up into no-man's-land between the lines, where they are certain to be killed by the Germans.

The other story is the tale of one of them, Manech (Gaspard Ulliel), who since childhood has been the sweetheart of the Brittany lighthouse-keeper's daughter Mathilde (Audrey Tautou); they are engaged to be married when he is called into the service. Mathilde has survived a childhood bout of polio, and walks with a limp. Manech becomes her legs, literally her carrier. Their romance is in the fairytale tradition of exquisite childhood loves that last into and beyond the loss of virginity, and it lends believability to her later crusade, which is that when she hears that he has been killed she refuses to believe it and begins her own search for clues that he might have survived. Manech himself is hardly in this story; once he leaves for the front he is gone from the film. It is Mathilde's story, and like any mystery she unravels one clue after another until - well, like much of life it has a bittersweet ending. Tautou, pretty as ever with her adorable overbite, is looking a bit mature, at 26, to play the twenty-year-old she is in the film, particularly against the very much younger-looking Ulliel; but no matter. It doesn't harm the story.

Mathilde hires a detective to track down information about each of the five men; we see him in his travels through France and in his reports back to Mathilde. At one point we learn that someone connected with one of the five has her own search going: for the men who condemned her lover so unjustly; to say more would give away a plot point, but it provides at least one scene of excruciating terror. This is not the pastoral film that its trailers led us to believe.

There is one sequence in Mathilde's search in which she locates the widow of one of the other men. The widow, Elodie Gordes, is played (in perfect French) by Jodie Foster, and she is magnificent as she tells her tale to Mathilde. She says she will only write it in a letter, but Jeunet shows it to us on screen as Mathilde reads it. It is a sad and powerful moment.

Some of the performances in "A Very Long Engagement" have the artificiality of the characters in Jeunet's "City of Lost Children," particularly Ticky Holgado as the detective; but Foster, and especially Jean-Pierre Becker as Lieutenant Esperanza, the one officer sympathetic to the needs of his men, are magnificent. It's hard for Tautou to get away from the sweetness of Amelie and the innocence of Senay in "Dirty Pretty Things, but she does show the iron will Mathilde needs to demand compliance, or at least acquiescence, in her obstinate insistence on searching for a dead man. We see in Mathilde the obverse of Amelie.

Jeunet, who made his reputation with the bizarreries of "Delicatessen" and "City of Lost Children," uses many scenes of multiple images here as a transition, where action in the background illustrates the dialogue in the foreground. Sometimes it works, but sometimes he abandons those second images too quickly, as though afraid that they'd take over the film; he should have let them do exactly that. On the other hand, his footage of the war in the trenches is magnificent, comparable in every way to the very best of "Saving Private Ryan." The mud, the rain, the water over shoetops, the pain, the pleasure of a cigarette while huddled in a little alcove; the blasted earth between the lines, the shell craters and the futile infantry charges, the arrival of Lieutenant Esperanza with strings of stolen sausages for his troops, who now are far too few to eat them all; all the things Jeunet sees in this ghastly war are exposed to us without pity or masking or sweetening.