'A certain feeling comes from throwing your good life away, and it is one part rapture." So begins Barbara Kingsolver's sprawling novel "Flight Behavior," in which a brooding young woman named Dellarobia Turnbow trudges up a mountain near her shabby eastern Tennessee home to meet a man she intends to take as her lover. Her beauty is still evident, despite her kitschy clothes and constant cloak of cigarette smoke, but her bright, curious spirit is ebbing, tarnished by poverty, two small children, hard-to-please in-laws and a mighty effort to keep loving Cub, the dull but kind man she married at 17. Her family, she notes wryly, is "an alliance of people at odds."

The anticipation of bliss and doom, the wages of adultery, slams to a halt when she reaches the summit and finds the forested valley below ablaze in shimmering orange. She hasn't worn her glasses, so can't tell right away what it is -- millions of migrating monarch butterflies taking refuge in the warm, wet valley.

Dellarobia's discovery launches one heck of a good story full of colorful yet subtle characters. The town's chief pastor, a blessedly likable fellow named Bobby Ogle, declares the insects' visit a divine miracle. An enigmatic entomologist, Ovid Byron, arrives from distant parts to pitch a trailer laboratory in Dellarobia and Cub's back yard, explaining that the monarchs once migrated to Mexico, but have been confused by dire weather there and could be near extinction if the Appalachian winter lingers. Others, including Dellarobia's in-laws, see dollar signs -- her hard-bitten, secret-harboring mother-in-law, Hester, wants to sell tours, while her tightly wound father-in-law, Bear, wants to log the trees the monarchs are blanketing, to hell with them, anyway.

So captivating is this grand, suspenseful plot and the many subplots rising and falling beneath it that it takes some time before we realize what this story is really about -- climate change. Kingsolver's social conscience has fueled all of her novels, but in this one, the issue plays second fiddle to the story, and frankly, that makes for a better book. She makes most of her characters doubters of global warming and indeed of most science, yet they are crafted with respect, not condescension.

Several scenes are downright brilliant as snapshots of lower-middle-class American life. Some are set in Ogle's megachurch. One takes place in a dollar store as Dellarobia and Cub argue about what to get their kids for Christmas, although what's really bugging them is their lack of money and love. In the best scene of all, Dellarobia goes shopping in a huge outlet store and is thrilled by its bargains in an astute snapshot of wealth and waste in America.

In the end, everyone's a little changed, Dellarobia most of all -- "It was hard to feel the remotest sympathy for any of the fools she had been," she ruthfully admits.

In her postscript, Kingsolver describes her own extensive study of climate change and monarch migration and reveals that the disaster in Mexico was real, but the events in Appalachia are "a fictional story within a plausible biological framework." In more ways than one, then, this is a work of imagination, but it also tells the truth in the way only good fiction can.

Pamela Miller is a Star Tribune night metro editor.