Through 50 Years of the Good and the Bad : THE RIVER BEYOND THE WORLD by Janet Peery; Picador; $24, 320 pages

The river in the title of Janet Peery’s lavishly written novel is, in one sense, the Rio Grande that runs between the worlds of Edwina Hatch, a wealthy Texan, and Luisa Cantu, the Mexican woman who serves her over a lifetime. It is a property of rivers, though, not only to divide worlds but, from vastly separate sources, to unite them in a common tidal ending.

The river, then, is also time. It is also, in this story of painful convergence, the vital current within two women of different cultures, status and expectations: a lordly tributary and a humble one; and a single ocean destination that trivializes the first and gives nobility to the second.

The start of “The River Beyond the World,” in the mid-1940s, is set out in two boldly contrasting sections. Luisa, barely adolescent, lives in the impoverished mountain village of Salsipuedes, or Get Out If You Can. After her mother dies, and she is impregnated by the local shaman for the yearly fertility rite, she does.

Peery writes this section in an ornate, Spanish-flecked style that can be irritating, yet in the end works very well. The young Luisa is a portrait of adolescent hunger, curiosity and adventurousness; she has a beguiling practical sensuality and an equally natural sense of religious mystery.

Nothing could be more different than the opening portrait of the high-strung, discontented Edwina. A second-rate Virginia aristocrat, a Scarlett O’Hara without suitors, she settles for Thomas Hatch, an east Texas fruit grower come east to buy tobacco. Her airs, graces and aspirations parch in the heat of the border town of Rio Paradiso. Thomas is a kind man who experiments brilliantly and profitably with new strains of fruit, but lacks fire enough to please Edwina.

She thinks of him, Peery writes--the author’s supple style has turned attractively particular--as “the bunny bread-man” and when Edwina tries to arouse him in bed “it seemed that his flesh had gone cool like the skin on a pudding.” She kindles herself on a neighbor, instead.

As a result, by the time Luisa has slipped across the border, given birth and been hired by Thomas as cook and maid, Edwina is expecting a child of her own. Luisa settles with scarcely believing delight in the plain wooden maid’s cabin with its bit of garden. To her, it will be a mansion. She raises her child, Tavo, and another child, Antonia--product of a night out with a soldier at the nearby base--and works with assiduous genius to keep a gleaming house for Edwina and improve her own.

“The River Beyond the World” relates the 50-year relationship of Edwina and Luisa through good fortune and tragedy. It is a duel and bristling dependency. Peery is charting the mutual distrust and mutual need of two nations and two national characters; yet in the main she does it with fictional grace through her two stubbornly individual personages.

The years pass. Luisa loves what frustrates Edwina: Thomas’ gentleness and scientific passion. She imagines him in bed with her; with an effort she avoids the slightest seductive gesture. Her children, Tavo and Antonia, and Edwina’s son, Raleigh, are inseparable playmates; as they grow older Edwina tries to keep them apart. Tavo will go off to fight in Vietnam and be killed; Luisa will not learn about it for weeks. She cannot read, and when an official letter arrives she thinks it is a deportation notice and hides it away.

Thomas withdraws his savings to buy a grand house for his fretful wife; when he loses the money by an odd mischance, he kills himself. Out of friendship--Thomas is esteemed throughout the county--the sheriff alters the records to make the suicide a murder by an unknown perpetrator. Edwina receives a fortune in insurance.

Antonia gets pregnant by Raleigh, home from college. Edwina takes her to Mexico for a nightmarish abortion attempt; like everything else she does, her action is a compound of self-interest, kindness and disastrous human obtuseness. More years pass. Antonia and Raleigh go their ways and flourish. Luisa, courted by a prosperous Mexican American farmer, learns to write and drive, and demands promotion from maid to housekeeper, with benefits. Despite her prickly care, Edwina grows feebler and more isolated.

Luisa is the larger, more original and more subtle character. Edwina, brittle and arrogant, is considerably more than a cartoon, though. She possesses courage, wit, a touch of poetry and a few good intentions, but they are immured in her presumptions of class and national superiority. The servant is the free woman, the mistress is in chains.

Peery’s novel, though never a polemic, replies to the current anti-immigration fanfare. It is not the labor of immigrants that the United States needs, but the humanizing dimensions of their culture.