What makes the Hollywood suits believe that being a “recovery agent” is a promising premise for a romantic comedy? Jennifer Aniston and Gerard Butler bombed in “The Bounty Hunter,” and now Katherine Heigl and Jason O’Mara follow suit, if not quite as disastrously, in this effort. “One for the Money” is a muddled, tonally clumsy adaptation of the first of Janet Evanovich’s Stephanie Plum books.

Actually Heigl doesn’t play a bounty hunter; Plum is a divorced woman who loses her job at Macy’s and, to make ends meets, badgers her bail-bondsman cousin Vinnie (Patrick Fischler) for a gig as a skip tracer despite having no qualifications for it. He reluctantly agrees, and also has to let her go after Joe Morelli (O’Mara), a cop on the lam on charges of having killed a drug-dealer off duty. Stephanie’s got a personal grudge against Morelli, who took advantage of her back in high school; but he’s got one against her, too, since she took revenge by running into him with her car. It’s pretty obvious from their first encounter that Morelli must be innocent and that they’re destined to get together in the end.

On the way to their preordained romance, however, they have to solve the mystery of the shooting that Morelli’s been indicted for. It turns out to be a very complicated business, involving a hooker who’s disappeared, her pugilist boyfriend (Gavin-Keith Umeh), his sleazy manager (John Leguizamo), a disfigured truck driver (Jack Erdie) and a motor-mouth witness (Leonardo Nam). But the identity of the villain is all too clear from very early on. Over the course of unraveling the crime, Stephanie learns the trade, courtesy not just of another cousin, a cop (Nate Mooney) but of an experienced tracer, a stud called Ranger (Daniel Sunjata), who’s exorbitantly helpful at every turn.

This part of “One for the Money” isn’t really comical—except for the contentious encounters between Stephanie and Joe. In fact, it can get pretty nasty, with a few characters getting killed (like the rival tracer played in a cameo by Fisher Stevens) and others assaulted (like a predictably sassy prostitute played by Sherri Shepherd) along the way. But mixed in with this part of the script are farcical elements involving Stephanie’s sitcom-quality family, worried Mom (Debra Monk), long-burning Dad (Louis Mustillo) and pushy, tart-tongued Grandma (Debbie Reynolds, mugging to the heavens as she goes through the most slapsticky routines). Naturally one of their bits of business involves trying to set Stephanie up with a likely husband—a sad-sack appliance dealer named Bernie (Adam Paul). And since the script is set in Trenton, all of them—along with other secondary folk like Vinnie and his secretary—talk in that “Jersey Shore” idiom that’s so “in” right now. It’s all very broad and not very funny.

Truth be told, the action and comic elements of “One for the Money” don’t mix terribly well. And having Stephanie prattle on in narration throughout the movie doesn’t help matters, only accentuating the makers’ inability to tell their story crisply through images and dialogue.

But still the movie, while hardly any great shakes, isn’t the disaster “The Bounty Hunter” (or Heigl’s “Killers,” with Ashton Kutcher) was. The star overdoes the frazzled spunk, but despite the inferior material retains her usual amiability comes through. O’Mara—who bears a curious resemblance to Aidan Quinn—makes a likable enough foil, and Sunjata (from “Rescue Me”) radiates smooth machismo. The supporting cast do what’s asked of them by director Julie Anne Robinson (who obviously has no taste for subtlety)—which mostly involves playing stark caricatures, but that’s the nature of such stuff. The picture is technically okay, with clear cinematography by Jim Whitaker. But it certainly doesn’t make much of Trenton look very attractive.

Heigl serves as one of the executive producers of “One for the Money.” Maybe she’s trying to go the Sandra Bullock route of fostering projects for herself in view of the fact that good leading roles for actresses aren’t exactly numerous. If so, she can take solace in the knowledge that most of Bullock’s efforts in that regard have been mediocre, too.