What lifts this movie above the usual run of dutifully sweet romantic comedies is the bright, fantasy-friendly sensibility of its two directors, Shari Springer Berman and Robert Pulcini. In the same way that their first feature, the 2003 "American Splendor," transformed the gritty precincts of Cleveland into an antic wonderland for the picture's oddball characters, "The Nanny Diaries" — with cinematographer Terry Stacey once again onboard — gives us a hyper-real rendition of Manhattan that's rich with fresh color and unexpected possibilities. This is the kind of place in which the star, Scarlett Johansson, can grab onto the big, red-umbrella logo of the Citigroup building in downtown TriBeCa, go sailing up into the sky with it and the conceit doesn't seem dumb — it's charming.

In this seductively idealized vision of New York, the picture somewhat resembles "The Devil Wears Prada" — without Meryl Streep, of course. But Laura Linney brings her own style of illumination to the character of a stone-hearted society matron who's both cruelly funny and, in the end at least, faintly sympathetic. Linney plays "Mrs. X," and she and her husband, "Mr. X" ("American Splendor" star Paul Giamatti), effectively set off Johansson's mild, grumbly warmth with some tangy narrative countercurrents. (The ungainly "X" pseudonyms are a survival from the popular 2002 novel on which the movie is based.)

Johansson plays Annie Braddock, who's just graduated from college with a major in business and a minor in anthropology. Annie's single mom (Donna Murphy) wants her to go right out and conquer the corporate world; but Annie's heart is really in anthropology — she's fascinated by the study of exotic cultural enclaves. One day in Central Park, she spots a little boy about to be hit by a motor scooter and snatches him away to safety just in time. The boy's distracted mother, Mrs. X, approaches and asks her son's savior who she is; but the woman mistakes Annie's name for "nanny" — possibly because she's in the market for one. Soon, for reasons that are of course not entirely persuasive, Annie finds herself installed in a cramped room in Mrs. X's vast Upper East Side apartment, providing the round-the-clock care for her son, Grayer (Nicholas Art), that his mother and father are too self-involved to supply.

The movie takes a wittily anthropological view of upper-crust tribal customs, and as Annie accompanies Mrs. X on air-kissing rounds among her fellow over-moneyed matrons, we marvel at their social armor of pricey bags and jackets and expensively blown-out hair, and their Canyon Ranch spa retreats and salad-centric lunches at Bergdorf's. Despite the fact that none of them has much to do beyond shopping and attending endless charity galas ("Conga for the Congo"), they all seem harried to the point of near-hysteria. ("Even though I don't have a job," Mrs. X gibbers, "I never seem to have enough time for myself.") They struggle to ignore their husbands' serial adulteries, and look upon their children — when they actually look at them at all — as inconvenient but necessary accessories. (Mrs. X orders Annie not to let little Grayer nap during the day: "I prefer him tired when I get home.") As for Mr. X, he's so wrapped up in his work (and an affair with a woman in his company's Chicago office) that he's given his son a business card to remember him by.

Helping Annie maintain her bearings as she journeys deeper into this strange new world are her best friend, Lynette (Alicia Keys, so radiantly engaging we wish there were a lot more of her) and "the Harvard Hottie" (Chris Evans), an ambient hunk with every woman's dream: actual emotional content. (Evans once again brings his deft intelligence to bear on what might have been a rote character.)

With its time-tested storyline — guileless outsider exposes the hypocrisy of a stuffy upscale social milieu — the movie might almost be "Miracle on 34th Street." But it's enlivened by inventive directorial quirks (emphasizing Mr. X's prickly remoteness, for example, by obscuring his face the first few times he appears). It's a good-natured picture, and it plays out to a predictable but satisfying conclusion. Hard-pressed moviegoers could do a lot worse these days. Scan your local listings.

Click here for Kurt Loder's review of "2 Days in Paris."

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