In the upscale, uptight town of Upchurch, Conn. (a fictional suburb that could be twinned with Stepford), every house is cookie-cutter perfect, every woman a trim, stay-at-home supermom raising overachieving toddlers. Or that's how it seems to mother-of-three Kate Klein, a Manhattan transplant whose imperfections make her feel like the town freak. When the most formidable of these ''terrifyingly capable-looking women'' is murdered, Kate learns that she and the victim shared a common friend. Naturally, then, it's up to her to crack the case. Jennifer Weiner has a gift for creating funny, flawed heroines (see Good in Bed and In Her Shoes), but as a suspense writer, she's still finding her footing. The Desperate Housewives gimmick throws Goodnight Nobody off focus, robbing us of Weiner's typically razor-sharp originality.