Meeting a significant other's parents for the first time is always a nerve-racking turning point in any relationship. Usually the experience isn't as disastrous as they set themselves up for, but there seem to always be those special cases where the two separate personalities simply clang together from day one. This is exactly what happens, and to an even more extreme degree, in the case of Charlotte "Charlie" Cantilini (Jennifer Lopez), a kind-spirited temp worker who meets her soul mate in the form of handsome doctor Kevin Fields (Michael Vartan). Their romance, which begins after three different meet-cutes, is a dream come true for Charlie until she is introduced to the other woman in Kevin's life—his on-edge, melodramatic, former talk show host mother, Viola (Jane Fonda). Viola doesn't like Charlie from minute one, believing her lowly lifestyle isn't fit for her more illustrious son, and her aversion spews outright hatred when the two of them become engaged.

Directed by Robert Luketic (2004's "Win a Date with Tad Hamilton!"), "Monster-in-Law" hits home some notions that will ring true for just about any audience member, but sinks into blandness more often than not. The opening half-hour, depicting the initial wooing between Charlie and Kevin, drags on and on as it takes too long to set up its premise and, even then, fails to ignite any detectable chemistry between the two characters. Their relationship, which doesn't work on its own, thankfully moves to the back burner as Viola bids war on Charlie, vowing to sabotage the wedding and scare her son's fiancée off. The heated, growingly malicious feud between Viola and Charlie is good for a few big laughs and some energetic moments, but they are interspersed between a larger number of stale jokes that fall with a resounding flatness. When Charlie mentions early on that she is allergic to nuts, for example, the eventual payoff to this movie-style information is so obvious that when it comes, it only elicits a roll of the eyes.

It doesn't help in the least that the screenplay, by Anya Kochoff, falls victim to some of the most depressing cliches of the Hollywood romantic comedy genre. If I never had to see another screen couple face the conflict of one of them walking in just at the precise moment when it seems as if the other is cheating on him or her with another man/woman, it wouldn't be soon enough. Conveniently, Charlie has a gay best friend (Adam Scott) and a gal pal (Annie Parisse) to talk to and confide in as they walk in and out of her apartment like meddling neighbors out of a sitcom. Even more discouraging is that "Monster-in-Law" is the type of movie where all problems could be solved in a matter of minutes if only the characters were smart enough to say the necessary things to clear up the problems. If this were so, of course, there wouldn't be enough material to fill up feature-length, which is a warning signal in and of itself that perhaps the story as written wasn't ready to be greenlit.

If there is a saving grace in "Monster-in-Law," it comes in the form of a show-stopping return to acting for Jane Fonda, whose last film was 1990's "Stanley & Iris." Fonda is so deliriously off-kilter as the borderline-psychotic Viola, and she relishes stretching her comedic skills to such a degree, that she might as well be the only one in the movie when she is onscreen. Particularly funny is a scene in which she and Charlie end up sharing a bed together—an old setup for a joke last glimpsed in "Guess Who" that this time puts a fresh spin on it—and another where Charlie tries to watch "A Nightmare on Elm Street" on TV as Viola talks her ear off, criticizing the movie to a ridiculous degree and going off on unrelated, one-sided conversational tangents. If anyone has ever watched a movie with a grandparent, they will be able to more than relate to this latter sequence, making it all the more rib-ticklingly accurate.

Paired against Fonda is Jennifer Lopez (2004's "Shall We Dance"), whose game turn as an inherently nice person pushed beyond the limits of what she is able to put up with would bring more attention to itself if not for her superior co-star. Accordingly, Lopez is perfectly fine, but her character's actions face the brunt of the screenplay's dumbed-down deficiencies; the ways in which she goes to get back at Viola in lieu of talking out her problems with Kevin occasionally make her just as unlikable as her future mother-in-law. Michael Vartan (2002's "One Hour Photo"), looking too gaunt and in need of a cheeseburger, is a bore as Kevin. His role is necessary but thankless, and Vartan does nothing to bring a voice to his character. Finally, comic Wanda Sykes (2000's "Nutty Professor II: The Klumps") basically plays her self-deprecating self as Viola's long-suffering assistant, Ruby. In sheer Wanda fashion, her wisecracks are just that—a series of expertly-timed, humorously-delivered zingers.

The intentionally over-the-top, at times cheerfully wicked, streak "Monster-in-Law" holds for most of its running time is greatly harmed by a cop-out conclusion that pushes the tone toward treacly, falsely uplifting mawkishness. Charlie deserves a happy ending, but the one she has been given strains plausibility in the name of righting all the wrongs that Viola has committed and sending viewers out with warm, squishy feelings. All director Robert Luketic has succeeded in with this flawed finale is threatening audiences with a sense of sickening sugar shock. "Monster-in-Law" yearns to be a little more wild and out-there than the average romantic comedy, but once a couple laughs have been earned, Luketic is prematurely satisfied and unveils the sinking reality of his film: "Monster-in-Law" is but a gutless, banal, disposable "safe" entertainment that lacks the courage of its convictions.