After a fifteen year absence from theaters Jane Fonda returns, inexplicably choosing a Jennifer Lopez vehicle as her means of re-entry. Her last movie was Stanley & Iris opposite Robert De Niro, which leaves Monster In-Law as quite a step down. But it is Fonda that lifts it above the plumbs of a typically bad Meet the Parents clone, and the movie might have been better served had it simply tossed out the Lopez character and given us more of her.

Alas there’s no escaping J-Lo. The over-exposed diva headlines the film as Charlotte, a brain dead, super cute gal who falls hopelessly in love with a doctor. Lopez plays her as if she’s some sort of floppy, valley-girl Muppet; a 5 year old trapped in the body of a 36 year old. It’s one of the worst performances of this year and Lopez, who’s proven she can do better, should be called to task for it. It doesn’t help that the movie wastes so much time setting up a relationship between her and Michael Vartan, the film’s pretty boy love interest. Vartan and Lopez have absolutely zero chemistry, and it’s a blessing that once Monster stops dragging around at manufacturing their romance that the two are less frequently together.

Things pick up a bit when we find out that her doctor boyfriend has a mother named Viola, played by Jane Fonda. Recently released from the looney bin, where she was imprisoned for attempting to strangle a Britney Spears clone in mid-interview, Viola is none to pleased with her son’s choice in girlfriends. Things only get worse when her forgettably handsome son announces his and Charlotte’s engagement. Long past the realm of sanity, the vicious Viola plots to destroy Charlotte and break up their impending nuptials, with her son none the wiser. With the help of her wisecracking assistant Ruby (Wanda Sykes), the pair form a wild comedic duo of bad natured punishers.

The men hanging around in the story are little more than props, hapless idiots unaware that it is the women in their lives who are the real power brokers. When Charlotte finally wakes up to her future mother in-law’s intentions, her personality does a sudden flip flop. Charlotte becomes every bit the dastardly villain her mother is, and the cutesy, dumb, dog-walker is cast aside in favor of someone disturbed and clearly amoral. It’s a huge misstep in the film when Charlotte starts feeding her husband’s mother dangerous medication. She’s become worse than Viola, and much less funny. Not only is it completely unlike the sweet, semi-retarded character J-Lo has been working so hard to bludgeon us with, but it also makes Charlotte terminally unlikable.

With no one worth rooting for, Monster in-Law grinds to a predictable finish. Everyone loves each other and the attempted murder perpetrated earlier in the script is swept playfully under the rug. Viola and her sidekick Ruby ride out of the film as odd anti-heroes, who you can’t help but think might have been right in trying to save Viola’s dimwitted doctor son from this ditzy bitch’s clutches.

Still, when Lopez isn’t in the way, both Sykes and Fonda garner tons of laughs as they carry out a personalized demolition derby on poor hapless Charlotte. Whenever those two are on screen, the movie flies along at a rapid and energetic pace. Fonda is wonderfully despicable, in the delightful tradition of over-the-top female villains like Cruella De Vil. A movie wrapped around the relationship between Viola and Ruby would have been a winner; as it is, sorting through the drudgery they’ve been plopped in is worth it if it means getting to their gut-busters.

With everyone sick to death of her, you’d think Jennifer Lopez would take a step back and pick a few smaller, more serious projects to regenerate her image. So far, that hasn’t happened. It’s business as usual here, another tired, big-budget romantic comedy whose only twist is that it’s ripping off popular Ben Stiller movies. But a bad script from Anya Kochoff and a lame performance by Lopez can’t dim the greatness Jane Fonda and Wanda Sykes. They’re a pitch perfect comedy duo and though she’s a controversial figure, Fonda has been far too long absent from the cinema. Without her, the film’s one-joke premise weighs it down like an anchor. It sinks with lackluster direction from Robert Luketic, and pales in comparison to others of its genre, even mediocre members like this year’s Guess Who. Luketic has done better with films in Win a Date with Tad Hamilton and Legally Blonde, but those benefited from a fresher premise. Monster in-Law is anything but fresh, and will hopefully bring an end to J-Lo’s unwelcome romantic comedy career.