VIDEO: The trailer for Nancy Drew

Andrew Fleming’s Nancy Drew kicks off with a mystery that eluded even our supersleuth. Holed up with two burglars in what a sign tells us is Calvary Presbyterian Church, Nancy gets away by posing as one of the statues of saints (!) that line the wall of the nave. Cut to, outside, Pastor Murray wearing a clerical collar and speaking in a thick Irish accent. Clue for Nancy: Pastor Murray started out as “Father Murphy.” Somebody must have decided that a Protestant church was more appropriate for Midwestern small town River Heights, but nobody remember to delete the Catholic leftovers. Oops!

That’s about the only slip-up in this smart, snappy film based on the series of girls’ books by “Carolyn Keene” that debuted in 1930. Rather than doing a period piece, Fleming and company make Nancy retro-relevant, a ’30s-’50s girl in 2007 LA who melds podunk and polymath. Her clothing — sweater sets, pastel plaids, Peter Pan collars, matching hairbands and scrunchies, knee socks, penny loafers, flannel PJs (in LA?) — seems hopeless, and while the other kids at Hollywood High are downing pizza and fries and Coke, Nancy sticks to finger sandwiches (crusts cut off) and carrot and celery sticks and milk. She calls the LAPD over a missing Pee-Chee folder; she even loses out in a car chase because she won’t exceed the speed limit.

But every time you’re tempted to make fun of Miss Prissy Principles, the film pulls you up short. In shop class, as the other kids struggle with clunky birdhouses, Nancy turns out a scale model of Paris’s Notre Dame cathedral, apologizing because she had time to complete only 12 of its 26 flying buttresses. The dress she’s made from her mother’s pattern has a Rodeo Drive saleswoman all a-twitter, and though her birthday party starts with the promise of a taffy pull, it ends with Nancy calling for a pocket knife and a ballpoint pen so she can perform an emergency tracheotomy. If patience, politeness, and perfection don’t suffice, she whips out one of housekeeper Hannah Gruen’s lemon bars, made from only the finest, freshest ingredients.

The set-up has 16-year-old Nancy (Emma Roberts, Julia’s niece) and her widower lawyer father, Carson Drew (Tate Donovan), taking the train to LA so Carson can line up some lucrative consulting work with attorney Dashiel Biedermeyer (Barry Bostwick). Nancy sees to it that they wind up renting the mansion of film star Dehlia Draycott (Laura Harring), who back in 1981 was found dead in her swimming pool. A mystery! Does the mansion’s gruff caretaker, Mr. Leshing (Marshall Bell), know more than he’s letting on? Will Hollywood High fashion plates Inga (Daniella Monet) and Trish (Kelly Vitz) stop being mean to Nancy and start helping out? Will Ned Nickerson (Max Thieriot), who drives Nancy’s blue roadster to LA from River Heights as a birthday present, get over her calling him just her “really good friend” in front of Inga’s pudgy, smitten 12-year-old brother, Corky (Josh Flitter)? And will Nancy be able to prove that single mom Jane (Rachael Leigh Cook) is somehow related to Dehlia?

Fleming has pitched his film to a tween audience: Nancy acts closer to 13 or 14, Ned is almost as baby-faced as Corky, Carson looks thirtysomething and recalls ’50s TV sit-com dads. Certainly there’s plenty of room for sequels. All arms and legs and her aunt’s smile, a younger version of Reese Witherspoon’s Elle Woods, Roberts is the Energizer Bunny that drives Nancy Drew; the other cast members (including an uncredited Bruce Willis) are warm-blooded caricatures, deadpan but not dead weight. This is a Hollywood movie that sends up bad Hollywood moviemaking, an ode to conservatism that excoriates conservative hypocrisy. And, like any good mystery, it challenges you to look closer. When Nancy sits down with her iBook and scrolls through Dehlia Draycott’s filmography on the Internet Movie Database, we get a glimpse of some early titles: The Bungalow Mystery, The Mystery at Lilac Inn. Actual films? No, they’re Nancy Drew books. Just a fleeting half-smile in a movie that’s far from clueless.