Katharine Heigl gained a lot of cinematic street-cred for 2007’s “Knocked Up.” Unfortunately, the all-too-easy-to-love actress has since squandered much of that goodwill in middling popcorn fare like “Killers” and “New Year’s Eve.” Her career now largely survives on the back of her non-threatening relatability (for the ladies) and her girl-next-door sex appeal (for the dudes).

With “One for the Money,” the “Grey’s Anatomy” alum once again exploits both of those qualities, somehow managing to deliver her most entertaining outing in years. Considering what those years have held however, that isn’t saying much.

Starting out a bit flat (well, not “flat” … uh, you know what I mean), Heigel eventually wins audiences over as Stephanie Plum, a cute-as-a-button junk-food junkie and down-on-her-luck everygal desperately searching for a new job and a new man.

Serendipitously, bail bondsman cousin Vinnie is looking for a bounty hunter, and former flame Joe Morelli has skipped his million-dollar bail while trying to beat a murder rap. Armed with a pistol and pepper spray, Plum fumbles through the high-risk world of bounty hunting, eventually shifting her priorities toward helping Morelli unravel the mystery of the criminal conspiracy surrounding him.

Of course, the mystery here is secondary. Audience members who can’t predict the identity of the unseen villain before the end of the first act should probably have their heads examined. And despite attempts to ratchet up the tension and drama near the end of the second act, “One for the Money” never earns its attempted gravitas.

More a romantic-comedy than a crime-thriller, the focus here is on the characters. In that sense, the film impresses, providing superior characterization than many movies of its ilk. Somewhere along the lines, though, something got lost in the translation from book to film.

The result is a wildly uneven film that is in turns quirky, plodding, grating, sterile and charming. With the camp factor turned way up, “One for the Money” could’ve been a blast. As it is, though, the film is a superfluous slice of pop entertainment. Harmless but valueless. Serviceable but inconsequential.

Part “Midnight Run,” part “The Bounty Hunter,” this flick is a lot like one of Plum’s treasured Tastykakes: sweet, fluffy and easy to digest, but completely lacking in nutritional value.

Maybe the book was better.

2 stars out of 5