Nancy Drew is a sleuth with couth, a 'tween dream. As played by twinkling star Emma Roberts (Julia's niece), Nancy is oblivious to jokes about her brainiac bent, dweeby dresses and mystery-mania.

Based on the popular books introduced 75 years ago, the girl detective in the new film is a Midwestern teenager with 1930s virtues - and virtue - who resists getting sucked into the moral black hole of millennial Hollywood. Anachronism is both the joke, and the joy, of Nancy Drew, in which a straight arrow shoots through a crooked universe and realigns its values.

When the small-town girl politely allows big-city Lolitas to take her for a makeover, the stylist eyes Nancy's knee socks and prim plaid dress and pronounces her so square she's hip, style messenger of "The New Sincerity."

One might call Nancy the avatar of Sherlock Chic, a description that equally applies to Andrew Fleming's buoyant film and to Roberts' sparkling performance as the first American Girl of pop fiction. According to Girl Sleuth, a 2005 book about Nancy's creation, fans of the series included Bette Davis, Mary Tyler Moore, Fran Lebowitz and Ruth Bader Ginsburg.

In the movie, Nancy is the clue-seeking daughter of a clueless dad (Tate Donovan), a Midwestern lawyer whose work takes him to Los Angeles. There, they rent a mansion haunted by a ghost (a spectral version of Sunset Boulevard's Norma Desmond), providing Nancy with a mystery to solve. Why is the spirit of dead movie queen Dehlia Draycott hovering in her crumbling mansion?

Toting a kit bag with tools that enable her to perform an emergency tracheotomy and safely scoot down a tall building, Nancy is a puzzle to her classmates at Hollywood High.

The standard-issue mean girls, Inga and Trish (Daniella Monet and Kelly Vitz) regard Nancy as a goody-goody with bad style. These girls who care only about boys and clothes are stunned when Nancy, oblivious to both, attracts hotties and compliments. (Nancy sews her own clothes from classic Butterick patterns.)

What's not to like about a girl detective who is a good citizen and better student, a leader rather than a follower, a resourceful seamstress who won't cut her clothes to fit this year's fashions?

I liked Nancy's spunk. So did the dozen 11-year-olds I had in tow.

Nancy Drew *** (out of four stars)

Produced by Jerry Weintraub, directed by Andrew Fleming, written by Fleming and Tiffany Paulsen based on characters by Mildred Wirt Benson, photography by Alexander Gruszynski, distributed by Warner Bros. Pictures.

Running time: 1 hour, 39 mins.

Nancy Drew. . . Emma Roberts

Corky. . . Josh Flitter

Thug. . . Craig Gellis

Charlie. . . Rich Cooper

Parent's guide: PG (mild violence, thematic elements and brief profanity)

Playing at: area theaters