Few modest lives have been so scrutinized as that of Laura Ingalls Wilder (1867-1957), author of the cherished "Little House" books — beginning with Wilder herself, who came to autobiographical fiction in her 60s, the proverbial late bloomer. In Caroline Fraser's magisterial and eloquent biography, "Prairie Fires," Wilder, in a willful act of reinvention, sanitized the people and events of her life with the support of her troubled only child, Rose Wilder Lane. "The real woman was not a caricature," as Fraser observes. "Her story, spanning ninety years, is broader, stranger, and darker than her books, containing whole chapters she could scarcely bear to examine."

Fraser divides her tome into thirds. The first details the familiar chronology, from the Ingalls family's sojourn in the Big Woods right up to Laura and Almanzo Wilder's move to Mansfield, Mo., following the Panic of 1893. Fraser draws heavily from Laura's nonfiction memoir, "Pioneer Girl," but fleshes it out with fresh bits from the diary of her younger sister Grace and pieces from Charles "Pa" Ingalls, whose voice reveals a keen mind at odds with his nomadic impulses and inability to provide for his family.

The second section covers the quiet years in Mansfield, before Wilder turned to writing as a vocation. Here Fraser hits her stride, painting a rich, provocative portrait of Wilder's career as a loan officer and community organizer, in addition to farm duties. Every dramatic story has a sexy, unforgettable villain — think Iago in "Othello," Stanley Kowalski in "A Streetcar Named Desire," Nurse Ratched in "One Flew Over the Cuckoo's Nest" — and the thorn in Wilder's side was the mentally unstable Rose, an indefatigable traveler and prolific journalist whose editing of her mother's manuscripts was brilliant, despite the tensions it spawned.

Now remembered as one of the three founders of American libertarianism (along with Ayn Rand), the erratic and petty Lane spent extravagantly, railed against enemies real and imagined, and increasingly shifted to radical conservatism, views her mother shared: "Profiled in the New York Times as 'on strike against the New Deal,' Lane portrayed herself as a Revolutionary war hero, opposing George III's onerous taxation to the end. … She ushered a reporter down to her cellar to inspect the ranks of home-canned food on her shelves. 'That's social security,' she declared."

From politics to art, "Prairie Fires" is virtually a double biography of mother and daughter and the work they forged in the crucible of their torments, creating an awesome achievement in children's literature. Fraser assiduously avoids the sentimentality of earlier books, such as Donald Zochert's "Laura," proving herself a fearless chronicler, adept at skewering sacred cows.

She's given us the definitive biography of a self-taught writer whose pull-yourself-up-by-your-bootstraps mythology cloaked the shame of poverty and airbrushed a life perpetually teetering on the brink of doom.

Hamilton Cain is the author of "This Boy's Faith: Notes From a Southern Baptist Upbringing," and a member of the National Book Critics Circle. He lives in Brooklyn.

Prairie Fires
By: Caroline Fraser.
Publisher: Metropolitan Books, $35.
Event: 7 p.m. Nov. 29, Magers & Quinn, 3038 Hennepin Av. S., Mpls.