“Birth” is not a comedy, but it’s impossible to take it seriously, either. It is about a woman who comes to believe that a 10-year-old boy is the reincarnation of her dead husband, which means there are scenes in which the grown woman and the little boy make moon eyes at each other. There is also a scene, I am sorry to report, in which the woman and the boy take a bath together, though thankfully there is no questionable behavior beyond that. (I think the bath is questionable enough, thank you.)

It takes care and precision to make an audience go along with a premise as peril-fraught as this one, and “Birth” doesn’t quite manage it. Director Jonathan Glazer, whose debut picture “Sexy Beast” demonstrated his skill, though not the subtlety he would need for this sophomore effort, goes to great lengths to make “Birth” seem like a respectable art-house film that has somehow wandered into the multiplex. The musical score is classical, the title fonts are elegant, the characters are generally quiet and restrained — this is a film that wants very much to be admired, not giggled at. But Glazer is hamstrung by Milo Addica (“Monster’s Ball”) and Jean-Claude Carriere’s oh-so-European and oh-so-absurd script.

Nicole Kidman, sporting a dreadfully mannish haircut, stars as Anna, a wealthy, repressed Manhattanite whose wealthy, repressed family is thrilled to see her newly engaged to a wealthy, repressed man named Joseph (Danny Huston). Anna’s husband Sean, a college professor (wealthy and repressed, one assumes), died 10 years ago and Anna still bears the scars of that loss.

Old wounds are reopened when a young boy (Cameron Bright) shows up at Anna’s family’s penthouse during the engagement party and tells her he is Sean — HER Sean, the one who died. His name really is Sean, that’s easily verified; he’s the son of a working-class couple in Brooklyn. But Anna’s-dead-husband-Sean? He’s certainly morose and somber enough to be part of the family, but still. No one believes in reincarnation, least of all Anna. Except then she begins thinking about it, and she talks to the boy, and she starts wanting to believe. Her family — including Lauren Bacall as her mother, Peter Stormare as dead Sean’s brother and Anne Heche as dead Sean’s sister-in-law — is appalled.

These are people who, being characters in a film that is always in danger of teetering over the edge into unintentional hilarity, cannot come right out and say the things they’re thinking, the things WE would be thinking. They don’t ask the questions they should ask. To do so would be to reduce the film from high-concept drama to lowbrow comedy. Even as it is, it often inspires embarrassed laughter. Nicole Kidman is an amazing actress, and her performance here is top-notch, but I doubt there is a child actor alive who could pull off the Sean role with the sincerity and believability it requires.

Is Sean really Anna’s dead husband? I like the direction the film takes with that issue; it’s certainly not what I expected. The problem is, it dawdles too long before it finally gets there. More than halfway through the film, we’re still at the stage where Anna is telling him, “You’re not my husband, you’ll get over me when you meet someone your own age.” The answers finally come, but they’re too little, too late.

C (1 hr., 40 min.; R, some nudity, a scene of strong sexuality (NOT between Nicole Kidman and the kid, thank goodness).)