Amy Tan's 'The Valley of Amazement,' on a courtesan's life And you thought they just had to lie there. According to Amy Tan's scrupulously researched novel "The Valley of Amazement," a courtesan in 1912 Shanghai would have had to master a hundred sexual positions, including "upward, backward, seated, standing, feet pressed on his stomach, legs in the air, the Bucking Horse, the Swaying Bamboo Shoots, Tigress Meets the Dragon, Oysters in the Turtle Shell" - all of it the distillation of "five thousand years of lovemaking, excitement, and boredom." And that's only half of it. Before taking her clients to bed, the true courtesan would have to seduce them with couture, plus an archive of zither music, all the while slaying them with perfectly calibrated gazes of longing. Let your eyelids fall halfway closed again - too much, that looks like you are asleep..... Let your mouth relax, your lips part - not that far. Now keep your eyes on him as your face flushes with uncontrolled pleasure. Suddenly, you gasp - softly with pleasure, not fright - and you show uncertainty - no, no, not a frown - a questioning look that changes to acceptance of fate.... Close your eyes, breathe quickly, warble uncontrollably to match the zither's tremolo. Then close your eyes and say 'Ah!' with ecstasy that devastates your senses. The recipient of this professional instruction is a virgin courtesan named Violet Minturn, who comes by her new job dishonestly. Her mother, a white American, was the owner of one of Shanghai's most exclusive bordellos - until the overthrow of imperial rule sent her scurrying back to San Francisco and left her daughter, half-Chinese, in the clutches of a syphilitic madam named Mother Ma (one of many splendid names in Tan's book). Violet is formally deflowered on her 15th birthday by the splendidly and ironically named Loyalty Tang. "I did not realize there would be so much blood," he confesses. She spends the next few years reaping cash and clothes and jewels from her besotted patrons only to discover that, at age 20, she is a "pickled peach, no longer new and intriguing." Fortune smiles in the form of a wealthy young American (whose name is Bosson Edward Ivory III). He has the inconvenience of a wife back home, but that doesn't stop him from falling in love with Violet and, soon after, impregnating her. Here is where fortune stops smiling, and the rest of "The Valley of Amazement" becomes a chain of calamities - Spanish influenza, kidnapping, impoverishment, sexual slavery, spousal abuse - extending more than 12 years and playing out against the backdrop of China's own socioeconomic miseries. In short, it's one Tan thing after another, and therein lies the episodic weakness of this book, which is epic in length but not in shape. After a couple hundred pages, the reader recognizes, with a slow-descending pall, that men will keep behaving badly (or, at best, weakly) and Violet will keep suffering. Not, however, without processing her feelings as efficiently as a guest correspondent for O magazine: "I needed honesty, and I was afraid to hear what his next confession might be. I needed complete trust in him, but I could not rid myself of doubts. Instead of loving him freely, I restrained myself, unable to let go. Nor would a chapter be complete without a string of expostulations from Magic Gourd, Violet's Thelma Ritter-ish companion, whose main job is to kvetch about the fine mess they're in: "Oyo! I am living in a chicken coop. Where are my eggs? Through all her hardships, Violet clings to the motto "Resist much, obey little," but she makes for a curiously bland and passive protagonist - a cork bobbing on her own life. It turns out that a far more compelling heroine has been waiting in the shadows the whole time. Late in the novel - too late - Tan zigs back a generation and reintroduces Violet's mother, Lucia, as a 16-year-old living with uncaring, free-thinking parents in late 19th century San Francisco. An affair with a Chinese art student leaves Lucia pregnant and penniless in Shanghai, but when an unexpected career path opens up, she seizes it with all the daring and moxie that her daughter lacks. Better still, her reappearance brings Tan back to the subject matter that has been her natural province since "The Joy Luck Club": the love-hate entanglements of mothers and daughters. In the novel's closing sections, you can feel Tan's deep pleasure in engineering a multi-generational, intercontinental reunion - even as you register your own relief that, after many hours of crawling through this "Valley," a peak has emerged. Bayard is a novelist and author of the upcoming "Roosevelt's Beast." The Valley of Amazement Amy Tan Ecco: 608 pp. $29.99