Tom Perrotta's thirtyish parents of young children are a varied and surprising bunch. There's Todd, the handsome stay-at-home dad dubbed "The Prom King" by the moms at the playground, and his wife, Kathy, a documentary filmmaker envious of the connection Todd has forged with their toddler son. Andthere's Sarah, a lapsed feminist surprised to find she's become a typical wife in a traditional marriage, and her husband, Richard, who is becoming more and more involved with an internet fantasy life than with his own wife and child.And then there's Mary Ann, who has life all figured out, down to a scheduled roll in the hay with her husband every Tuesday at nine P.M.They all raise their kids in the kind of quiet suburb where nothing ever seems to happen - until one eventful summer, when a convicted child molester moves back to town, and two parents begin an affair that goes further than either of them could ever have imagined.