Isabel's Bed

Isabel's Bed Elinor Lipman (Pocket Books, $20) This brash novel is as shallow as a wading pool, but a trillion times more fun. Dumped by her ''malcontent boyfriend of twelve years,'' unpublished novelist Harriet Mahoney flees town, hiring herself out to ghostwrite an autobiography in Cape Cod. Her new employer (and roommate) is Isabel Krug, whose claim to fame is that she was in bed with a rich man when his wife caught them-and shot him. Yes, it's deft and funny, but the growing friendship between trashy, blond Isabel and shy, acerbic Harriet is really where Lipman's skill shines. In other hands, this classic Odd Couple contrast could turn musty real quick, but Lipman keeps it- and the ending-swerving. Sit back. Enjoy. Get your quota of social significance somewhere else. B+ -Kate Wilson