Once in a while a piece of glossily meretricious pulp like “Fatal Attraction” or “Basic Instinct” can strike a chord with the public and become a cultural phenomenon. That’s not likely to happen with “Unforgettable,” which may fulfill the promise of its title, but in an unwelcome way—it’s so bad you might be unable to expunge it from your memory however hard you try. (On the other hand, it could go the way of the many other pictures with the same title—like one from 1996 starring Ray Liotta. Bet you don’t remember it.) Essentially a Lifetime woman-in-peril movie with more gloss and explicit sex and all the clichés one expects of the genre, it’s so ludicrous that audiences will likely be chortling derisively before the first half-hour is over.

Rosario Dawson is put-upon Julia Banks, who leaves her job as an on-line editor to relocate to California and live with her boyfriend David Connover (Geoff Stults), an erstwhile Wall Street broker turned up-and-coming micro-brewer. Their life together as they prepare to marry will involve Julia’s getting to know David’s little daughter Lily (Isabella Rice).

The situation is complicated by the presence of Tessa (Katherine Heigl), David’s ex, who has—for reasons not explained—turned over primary custody of Lily to David. A beautiful, controlling woman (with, it will eventually be revealed, a dark psychological history), she’s very demanding with Lily, and though she affects goodwill toward Julia, she’s actually planning to use her daughter as a tool in breaking up the happy new couple and getting David back.

But that’s only part of her malicious plan. She also steals information from Julia’s phone that she uses to contact Michael Vargas (Simon Kassianides), an abusive former boyfriend against whom Julia had taken out a restraining order, and persuade him that Julia wants to resume their relationship. Her aim is to create a cyber-trail that will identify Julia as the person inviting Michael to come to her, and when he does she will use the meeting to her own nefarious purpose.

Clearly “Unforgettable” conforms to the crazy-ex template, but the script by Christina Hodson and David Leslie Johnson makes a laundry list of mistakes along the way. One is to include a prologue—a police interrogation of Julia—that foolishly telegraphs what then follows in an extended flashback. Another is to make David the typically clueless guy who’s easily taken in by his ex. (Stults doesn’t help matters with his bland performance.) A third is to include in the mix Tessa’s mother (brittle Cheryl Ladd), whose brusquely contemptuous treatment of her daughter is used as an all too simple means of explaining Tessa’s nuttiness (as well as her attitude toward Lily). The multiple twists at the end—one so banal that it’s practically obligatory, the other a bust—end things on a down note, too. (An incidental point: David is brewing beer, but over dinner—even with his financial backers—he’s always serving wine. Isn’t his product good enough for them?)

The most serious shortcoming in the movie, though, involves the leading ladies. Julia is meant to be sympathetic, but the character is simply too dumb to generate much empathy, though Rosario emotes to the skies trying to get us to root for her. Heigl aims to channel the Glenn Close of “Attraction,” but Tessa remains more statuesque than scary. One doesn’t want to give away too much, but there is a catfight between the two toward the close that’s likely to induce howls of unintended laughter. To be fair, the script does include one surprise in the fate of Julia’s chum Ali (Whitney Cummings); you might expect her to wind up differently than she does. Or maybe she just became an afterthought to the writers.

“Unforgettable” is the directorial debut of long-time producer Denise Di Novi, which necessarily raises the issue of why a woman would choose a trashy female-centric piece like this to initiate a new career. It looks fine, though: Nelson Coates’ production design and Marian Toy’s costumes bring a hint of elegance to the visuals, with Heigl’s clothes especially attractive. Cinematographer Caleb Deschanel, however, is too gifted a craftsman to have wasted his time on such schlock, and Toby Chu’s score is overbearing, mercilessly underlining the supposed sense of menace.

Heigl’s recent TV series “Doubt” was unceremoniously yanked from the schedule by CBS after only two weeks. It will be a miracle if “Unforgettable” lasts in theatres even that long.