In Amy Tan's newest novel, she returns to familiar ground: the relationships between mothers and daughters amid moral ambiguity.

But in "The Valley of Amazement," Tan proves there are plenty of surprises left when the mothers and daughters inhabit the world of courtesans in turn-of-the-century Shanghai. For 600-plus pages, she delves into the secrets of the women who lived on that precarious rung of society, tolerated and even celebrated but not fully accepted.

Tan hasn't written a new novel in eight years but "The Valley of Amazement" was worth the wait. This novel, which explores the divides between East and West, sexual fantasy and sometimes-bitter reality, is a saga that leaves you weary in the end — in a good way. You climb the mountain with the characters, struggle to learn that foreign tongue, feel renewed by love and torn apart by losing someone dear.

The story begins where so many of Tan's books do — including her famous debut novel, "The Joy Luck Club" — with a mother and daughter, Lulu and Violet. Lulu is a white American woman from California who abandoned her life in a moment of passion to follow her Chinese lover to Shanghai, only to realize that she has no place in that world and no ability to return to her own, now that she's pregnant.

Lulu becomes the owner of a top courtesan house, and that's where young Violet learns about the arts of the bedroom — and also that she is half Chinese, a person who fits nowhere. When her mother is tricked into leaving Violet, the girl begins her own voyage of survival, turning to the only life she knows, as a courtesan. Later, when Violet becomes separated from her own child, Flora, she comes to understand her mother's anguish.

The genesis of the book is intriguing on its own. While reading a book about Chinese courtesan culture, Tan came across a photo of 10 women dressed in clothes she recognized as identical to those her grandmother wore in one of the author's favorite photos. The women in the photo, captioned The Ten Beauties of Shanghai, were courtesans. Tan began to wonder what secrets her grandmother might have kept — and a novel was born.

Tan has said that the history of women in her family has been about survival, persistence, passion and tragedy, and that's clear in the book. When the girls, first Violet and then Flora, are separated from their mothers, their pain becomes the steely core of their beings. Passion is a luxury that generally comes to a bad end; most of the men betray the women or turn out to be weak or die early. And survival is a hard-won commodity.

The tales from the courtesans' bedrooms are an eye-opening study in the calculations, ploys — and acting chops — that women cultivate to survive when men have all the power. Courtesans-in-training are schooled in stories with sexual undercurrents — Peach Blossom Spring is ostensibly about immortality — and warned about the various types of clients, including the dangerous Lover of the Bloodcurdling Screams.

Courtesans work toward the Four Necessities, "jewelry, furniture, a seasonal contract with a stipend, and a comfortable retirement. Forget about love. You will receive that many times, and none of it is lasting," Tan writes in the voice of Magic Gourd, the woman who prepares Violet for her deflowering "debut."

Tan portrays the courtesans in a half light, powerful in youth and beauty but always aware that the street is only one unsuccessful "season" away.

Even when she allows her characters to break free from their circumstances, Tan offers little indulgence for what they've been through, no easy, feel-good resolution to wrap up the plot line. Tan is a clear-eyed realist who believes women have to be the heroes of their own lives. But sometimes, she says, we can find new ways of seeing that bring us contentment, peace and, yes, even happiness, when we least expect it.