Starring Katherine Heigl and Jason O’Mara. Rated PG.

In Hollywood, dying your blond hair brown usually means you want to be taken more seriously. But in One for the Money, Katherine Heigl opts for more silliness while toughening up her good-girl image with pleasing panache.

Here, she plays Stephanie Plum, working-class product of Trenton, New Jersey. That’s the lead character in 18 numerically themed comic mysteries churned out by author Janet Evanovich since 1995. The movie, like the first book of the series, finds Plum newly fired and recently divorced, and therefore open to jobs for which she seems unsuited, such as becoming a paid-per-perp bounty hunter for her bail-bondsman cousin.

If you’ve seen Jason Reitman’s Young Adult, you may be reminded of Charlize Theron as the delusional pulp-fiction writer who wreaks havoc in her hometown. Our star doesn’t have Theron’s dark streak, and this character is the opposite of cynical. Despite her junk-food diet and equally spotty life-option menu (even while looking approximately like Heigl), Plum is almost giddily optimistic—especially when it comes to bringing in one Joe Morelli (Life on Mars star Jason O’Mara), a rogue cop to whom she just happened to lose her virginity in the back of the Tasty Pastry shop when she was 16. And then the bastard never called.

The film has a snappy rhythm, thanks to Julie Anne Robinson, who directed the schlocky Miley Cyrus vehicle The Last Song and many episodes of Grey’s Anatomy. It has a TV-movie look, and the script, credited to three writers, gets more illogical as it moves along. Still, things are buoyed throughout by an amiable cast, including John Leguizamo as a friendly gym manager, Rescue Me’s Daniel Sunjata as a stud-muffin bounty-hunting pro, and Sherri Shepherd as a helpful hooker. Oh, and Debbie Reynolds—still blond—shoots a turkey. Need I say more?

Watch the trailer for One for the Money.