"Early Warning," the second volume in a projected trilogy by Jane Smiley that began with "Some Luck," continues to follow the fortunes of the Langdons, an Iowa farm family, as they multiply, diversify and embody the American experience. This book covers the years 1953 through 1986 and a broad spectrum of geography, character and circumstance.

Dickensian in its breadth and detail, the novel is distinctly un-Dickensian in its sense of purpose — or lack thereof. It reflects a distinctly modern understanding of life — and fiction — as unplotted except in the direction and shape that each character, in uneasy alliance with chance, chooses and views as a meaningful pattern. Even the one relatively "literary" twist the novel takes is plausible, well prepared for and significant only within the web of the story's extended family.

The modern world being what it is, it is within that web that significance resides, and there every event resonates, from the birth of a baby (there's a doozy) to catastrophe on a grand scale (Vietnam, Jim Jones, AIDS — and for some of these characters, well, the election of Ronald Reagan). The atomic threat (thus the title) that hovers over it all is, as spelled out by one character in the course of her crazy therapy, Ragnarök, "the end of the world, in Norsk." "Götterdämmerung. Apocalypse?" the doctor asks, helpfully.

With the death of the gods in the offing, mere mortals such as the Langdons (and the rest of us) are left to their own devices, and Smiley is simply brilliant at describing what that entails: for the last of the family left on the farm, for the weapons manufacturer and the wife of the CIA insider, for the high school teacher and the professor, for the homemaker and the radical.

Proceeding from year to year, alternating between the perspectives of the Langdon offspring and their children (and their children), the book immerses us in the meaningful minutiae of daily life as experienced by the old and young (even an amusingly convincing toddler), the aimless and enterprising. And when matters of greater social or cultural consequence touch these lives, we see and feel them as a character does — the Vietnam War through the point of view of a young soldier, a grieving sister, a protester; AIDS through that of an abstemious gay man; the grain embargo through that of a farmer.

Whether these characters are debating politics, escaping an oppressive husband, facing grave illness, seeking solace in a cult, falling in love, making a deal, going through basic training or caring for a child, their doings are conveyed in intimate detail, felt and understood on each character's own terms.

Midway, one young woman reflects on the exhilaration of a horse midjump. "As with every arc, she knew, there was a moment of weightlessness in there." And Smiley delivers such moments, too, when among the daily maneuvers and mundane details the arc of her narrative lifts us, and we see for an instant how anything might happen.

Ellen Akins is a novelist and a teacher at Fairleigh Dickinson University. She lives in Wisconsin.