LOS ANGELES -- It's easy to understand why Hollywood loves doing business with author Nicholas Sparks.  His books are huge best-sellers, and several of the films adapted from his novels -- "Message in a Bottle," "The Notebook," and "Dear John" -- have achieved impressive box office grosses. The latest Sparks adaptation, "Safe Haven," will probably continue his winning streak, especially with its Valentine's Day opening pegged to lure female fans.  A thriller element that has not been present in earlier Sparks movies is designed to draw reluctant male viewers to see the picture, but they won't respond with the same enthusiasm as his core audience of woozy romantics.

The mystery plot recalls a 1991 Julia Roberts movie, Sleeping with the Enemy, in which the heroine fled an abusive husband and tried to re-invent herself in a brand new community. In this case our heroine, Katie (Julianne Hough), runs away from a toxic marriage in Boston, boards a bus, and on a whim gets off in a small seaside community in North Carolina.  There she meets a sensitive widower, Alex (Josh Duhamel), raising two young children on his own.  Because of their troubled histories, they approach each other warily, but there's little doubt about where their relationship is headed.  Before long, however, a nasty blast from Katie's past arrives to threaten her newfound bliss.

The first problem with the film is that the burgeoning romance is too flat to generate intense audience empathy.  Alex's daughter, who barely remembers her mother, warms to Katie immediately, but her older brother has a harder time with his father's new relationship.  Still, this complication isn't especially well developed in the screenplay by Dana Stevens and Gage Lansky.  In addition, the two main characters are such paragons that there are no real psychological impediments to their union. To jack up the tension, director Lasse Hallstrom (who also helmed the film "Dear John") keeps intercutting scenes of a grim, hard-drinking Boston cop (David Lyons) determined to track Katie down. But the gauzy romantic interludes prove to be something of a yawn.  When her nemesis finally arrives in North Carolina, the film does develop some effectively suspenseful moments. But the drama is a long time coming.

A related problem is the casting. The best Sparks movie, "The Notebook," had the strongest cast, with talented newcomers Ryan Gosling and Rachel McAdams balancing seasoned veterans James Garner and Gena Rowlands. To put it as charitably as possible, the actors in "Safe Haven" are not in the same league. Hough, better known as a singer and dancer than a dramatic actress, is likably spunky, but Duhamel fades into the background, and there are no lively supporting players in the ensemble. Perhaps the biggest disappointment is that Hallstrom, who burst into prominence with his fine direction of child actors in the Swedish film "My Life as a Dog," fails to draw vivid performances from the two actors cast as Alex's children.

Hallstrom's direction is generally lackluster. The picture is certainly competent, but a dozen other journeyman directors could have executed this piece just as efficiently. It's hard to see much evidence of the talent that brightened "My Life as a Dog," "The Cider House Rules," or even "Chocolat." The seaside locations are tenderly evoked by cinematographer Terry Stacey and production designer Kara Lindstrom, but the film isn't visually memorable or dramatically vibrant. It does, however, have one sentimental surprise at the end that testifies to Sparks' storytelling shrewdness. This last-minute twist is shameless and stupefying, but it demonstrates why Sparks has an army of fervent readers.  His fans will no doubt swoon over this tear-jerking finale, even while critics stare at the screen with jaws open in disbelief.

"Safe Haven," a Relativity Media release, is rated PG-13 for thematic material involving threatening behavior, and for violence and sexuality. 115 minutes.