This ends up as an edge-of-the-chair thriller, but it is all the more involving because the mystery doesn't even surface until the novel is well under way. Before that you're caught up in high school sophomore Dorothy Coughlin's culture shock when she, a policeman's daughter from Newburgh, New York, takes a summer. (1956) job as mother's helper on a luxurious Pennsylvania estate and finds her Catholic school values in conflict with her envy and ambition--and with the eventually victorious temptation to lie, steal (a discarded old pair of riding boots), and spy on her employers. Dorothy likes disheveled, distracted Mrs. Hoade who drinks a lot, throws $200-dollar parties, devotes the summer to writing a ridiculous Amish cookbook, and has recently given birth to a mongoloid child whom, Dorothy is told, she keeps locked away with a nurse in an outlying cottage. Dorothy's snooping reveals that it is not the baby but a dying grandmother who has been locked in the cottage and hassled into signing a will. But when she realizes that it is not the sinister, shady Mr. Hoade but his wife who has been browbeating the old lady--and not the Hoades but the grandmother's intended heir, her innocent German nurse, who would suffer from the exposure--Dorothy puts aside both her dream of glory and her rigid rules of conduct (ironically in accord for a change) and decides at last to ""leave well enough alone."" Dorothy's ethical struggles are both serious and funny, and her growth toward moral sophistication is well grounded in the suspenseful plot and smashing setting.