The opening sequence of "Birth," a suave and brooding gothic tale directed by Jonathan Glazer, is a small tour de force. It takes a perfectly ordinary urban moment -- a jog through Central Park in wintertime -- and turns it into a visual and aural overture for the film's layered and shifting moods.  As a long tracking shot follows the dark-hooded jogger past heavy, snow-shagged trees (photographed by the excellent Harris Savides), Alexandre Desplat's score offers a compressed foreshadowing of the emotions Mr. Glazer will go on to explore, nudging dissonant registers of feeling into deceptively smooth harmony. A tinkle of childish whimsy slides into a swell of string-heavy melodrama, which disappears into deep bass tones full of menace and foreboding.  The music sharpens your attention and throws you a little off balance, which is apt preparation for what follows. The runner suddenly collapses beneath an underpass, as if caught in the darkness between two worlds. The rest of "Birth" takes place in a similar limbo. Like one of Henry James's ghost stories, it stakes out an agnostic, ambiguous position on the existence of supernatural phenomena.  At times, the movie seems to be headed for a neat, either-or resolution -- threatening to become either a highbrow version of "Ghost" or a supremely elegant episode of "Scooby-Doo" -- but its interests turn out to be more psychological than supernatural. The screenwriters, Milo Addica (who was a co-writer of "Monster's Ball"), Jean-Claude Carrière (whose long career includes two decades of collaboration with Luis Buñuel) and Mr. Glazer are more concerned with atmosphere than with explanation, and the key to appreciating "Birth" is not so much a suspension of disbelief as an anxious surrender of reason.  The man who died in the park was named Sean, and 10 years after his death his widow, Anna (Nicole Kidman), is preparing to remarry. She and her fiancé, Joseph (Danny Huston) live in a vast East Side apartment owned -- ruled may be the better word -- by Anna's mother, played with steely wit by Lauren Bacall.  On the night of Joseph and Anna's engagement party, a young boy with close-cropped hair and a round, serious face shows up claiming to be Sean and pleading with her not to marry Joseph.  The boy's deadpan persistence throws the household off balance. Is he playing a mean prank or indulging a childish fantasy? Or could he be telling the truth? Cameron Bright, who plays Sean (which happens to be the boy's real name), gives an unnervingly controlled performance. The film's delicate mood of indeterminacy rests on his shoulders, or rather in his smooth, inscrutable face. His character represents a premise that is absurd, even ridiculous, but for "Birth" to work it must be addressed with utter seriousness, even solemnity.  And somehow, in Mr. Glazer's hands, it does work. The hushed, claustrophobic ambience of high privilege and repressed feeling occasionally cracks, as this horror movie reveals itself also to be a rich, agonizing melodrama and a dry comedy of manners set in a fantasy Manhattan of crème caramel wainscoting and black-tie evenings at the opera.  Both the humor and the pathos arise from the attempts by the stiff, decorous adults to deal with the unwelcome child in their midst. Anna's mother humors him ("so how is little Mr. Reincarnation enjoying his cake?"), while Joseph drifts from tight-jawed skepticism toward violent jealousy.  The most important response, of course, is Anna's, and it is also the most complicated. Ms. Kidman, her hair cut short and dyed dark red, conveys both the toughness of a woman who has pulled herself together after a traumatic loss and the vulnerability of someone whose grieving has remained incomplete. As much as Mr. Desplat's score or Mr. Glazer's sly pacing, it is Ms. Kidman's face that holds you in a spell of uncertainty.  She has an uncanny ability to register large feelings with tiny gestures, which Mr. Glazer exploits by filming her in long, silent close-ups. Without Ms. Kidman's brilliantly nuanced performance, "Birth" might feel arch, chilly and a little sadistic, but she gives herself so completely to the role that the film becomes both spellbinding and heartbreaking, a delicate chamber piece with the large, troubled heart of an opera.  "Birth" is rated R (under 17 requires accompanying parent or adult guardian). It has some scenes of nudity and sexuality.  Directed by Jonathan Glazer; written by Jean-Claude Carrière, Milo Addica and Mr. Glazer; director of photography, Harris Savides; edited by Sam Sneade and Claus Wehlisch; music by Alexandre Desplat; production designer, Kevin Thompson; produced by Jean-Louis Piel, Nick Morris and Lizie Gower; released by Fine Line Features. Running time: 100 minutes. This film is rated R.  WITH: Nicole Kidman (Anna), Cameron Bright (Young Sean), Danny Huston (Joseph), Lauren Bacall (Eleanor), Alison Elliot (Laura), Arliss Howard (Bob), Michael Desautels (Sean), Anne Heche (Clara) and Peter Stormare (Clifford).
A O Scott reviews movie Birth, directed by Jonathan Glazer and starring Nicole Kidman and Cameron Bright; photo (M)