Rosario Dawson, left, and Katherine Heigl star in "Unforgettable."

Warner Bros. Pictures

One of the funniest movies, which is destined to be televised along with its lower-budget kin in the not-too-distant future, is “Unforgettable,” a high-camp melodrama that will appeal to those who long for the catfight days of television shows such as “Dynasty.” The unintentional hilarity that ensues after the set-up will be delicious to anyone who enjoys “so bad they’re good” films.

Aside from its comedic factor, this is a television screenplay dressed up in feature film attire.

Rosario Dawson plays Julia, a young woman who is about to marry David (Geoff Stults, “J. Edgar”) the man of her dreams and become a stepmother to his daughter, Lily. Julia’s experience with domestic violence some time before still haunts her.

Katherine Heigl is David’s ex-wife Tessa, who cannot stand the thought of someone else helping to raise the little girl she had with David. She still loves David and eventually becomes determined to thwart the romance he has with Julia. She’s a lot like the Betty Draper character from television’s “Mad Men.”

Cheryl Ladd (yes, *that* Cheryl Ladd from television’s “Charlie’s Angels”) plays Tessa’s overbearing mother, who earns the nickname “Cruella Chanel” at one point.

At first, Julia does all she can to show the little girl that she cares about her. She provides a special quilt for the little girl, who refuses to use it. When Tessa realizes just how serious David and Julia are, she begins to scheme about how she can break them up. When Tessa finally becomes completely unhinged, we watch her take extreme measures to torment Julia.

We see Tessa begin to unravel even more as the bond between Julia and David grows more intense. Her psycho-ex takes on a more and more sinister tone. In one scene, we see her combing her daughter’s hair and saying “Now you're perfect. Just like Mommy.” In another scene, Julia and Tessa have a stand-off about how to handle Lily’s fearfulness of riding a horse.

Eventually, Tessa becomes an out-and-out monster. When murder enters the picture, we know that the script will include a catfight that’s every bit as outrageous as any goofy soap opera scene.

Out of all the ensemble, it’s Dawson who delivers the most sincere performance. Part of that is because her situation is the most honest part of the script, which does indeed nail the sort of terror that people experience long after a domestic-violence experience is over. Julia never really feels safe, and doesn’t want to reveal what happened between her and her ex-boyfriend.

That’s a real-life scenario that’s never funny. But this movie makes it inappropriately giggle-inducing.