At the beginning of Monster-In-Law, Jane Fonda's freshly-fired news anchorwoman Viola berates a young blonde interviewee for being "insipid" - an adjective that starts to become increasingly appropriate for the film itself. While showing initial signs of intelligence (she also scolds the girl for not being politically aware), Fonda's character shifts into cartoon dragon mould, acting nonsensically for supposed comic effect.
When she discovers her son Kevin (an underwhelming, rarely-seen Michael Vartan, One Hour Photo) plans to marry polite, mild-mannered Charlie (J-Lo), she takes an inexplicable dislike to the notion (the idea that she wants her son all to herself just doesn't wash). Launching into action, she fakes mental illness and moves in with Charlie while Kevin is away, insisting on interfering with the wedding and annoying Charlie as much as possible.
There are potential laughs in some of Viola's schemes, such as giving Charlie a dress one size too small (cue Jennifer Lopez bum jokes), but they're poorly executed. And despite her strong on-screen presence Fonda doesn't use her comic ability to best effect. Lopez, too, suffers from a lack of comic talent and feels miscast once again as the poor little girl. Peripheral characters such as Charlie's gay friend Remy (Scott) and Viola's assistant Ruby (stand-up comedienne Sykes) have a mere handful of one-liners to offer.
Without a strong comic thrust, it's left to the plot to entertain, but there's no tension in this one-note story. The jerky editing gives little sense of timing or urgency ("I can't believe I'm getting married in a week," Charlie suddenly informs us) and there's rarely any sense of a real threat from Viola (why should we care, anyway, when Charlie's such an unsympathetic character?). Charlie's decision to turn the tables brings a spark of interest, but the opportunity for revenge is under-used, making this a pale imitation of successful wedding/family-themed comedies such as Meet The Parents.