I slipped off my clothes and dove into the pool. We are 96 percent liquid. There is nothing more sensuous than a good splash against naked skin: the initial rush of cold, the smooth acquiescence of inner fluid to the outer mantle of wet. Thirty-two-year-old Audrey Hastings swims a mile each day in her backyard pool: sixty-six laps. These meticulously counted crossings are the balm for her frustrations as a new mother, and her hedge against the insecurity she feels upon discovering her first gray hair. But the smooth waters through which she so assiduously glides grow cloudy when it becomes crystal clear that her good-looking, easy-going husband has begun an affair with a comely co-worker named Kim--who resembles Audrey, ten years younger.         Audrey rages and stews and swims while contemplating this threat to her very existence. A fan-tasy of revenge--taking a younger lover of her own--becomes real when Audrey catches the eye of a sexy grad student at the park where she takes her two-year-old, Gina, to play.         Audrey hesitates, resists, succumbs. And Au-drey learns that the consequences of jealousy, suspicion, and adultery can be more disastrous than she ever imagined.         Precise, intelligent, and intense, 66 Laps is an altogether irresistible novel written with scalpel-like precision.