There can't be many Americans over age 30 who haven't seen a reproduction of the Dorothea Lange photograph called "Migrant Mother." It was taken in 1936 at a California pea farm. Florence Owen Thompson, one of the pickers, 32 and the widowed mother of seven children, allowed Lange to take six pictures, the last one a close-up portrait of her face, two of her children nestled into her neck, facing away. A severely cropped version is used as the cover illustration of "Mary Coin," Marisa Silver's imagined version of Thompson's life. The photo captures a tension between desperation and stoic endurance that the novel unpacks. A nervous hand at her chin, a bony, careworn but still handsome woman looks out sideways, her brow furrowed, her mouth set.

The photo is both a cheat and a ghostly, now mysterious alter-image to an aged Mary, looking at herself in a gallery of Depression-era pictures. It's a cheat because the woman in the photograph will never have to contend with the harsh future in store for Mary. Moving from farm to farm, never sure of work, living in shacks or tents, trying to keep her malnourished brood going, she never has solid ground beneath her feet. She learns early that "living was … [a] trick played on fate for as long as you could until fate got the better of you."

Interwoven with Mary's chapters are the accounts of two other people, one of them, Vera Dare, based on Lange. Starting as a society photographer, she grows dissatisfied with the work and turns to the documentation of farm workers and their back-breaking, underpaid labor. They endure conditions close to slavery. They are free to leave, but that might mean only the freedom to starve.

Except for her visionary portrait of Mary, Vera's life is the stuff of middle-class worry. She bears two sons to a philandering husband, finds a decent second spouse and eventually dies of cancer. In what seems a kind of commentary on Mary's take on her picture, Vera thinks, "A picture doesn't bring someone to life. A picture is a death of the moment when the picture was taken. Whenever you look at a picture, time dies again." The remark is pompous where Mary's is plain.

The third protagonist is Walker Dodge, a historian who eschews the Big Picture to burrow in attics in search of how daily life proceeded for ordinary working people. He is the grandson of Charles Dodge, the owner of a large orange ranch during the Depression. Cleaning out the family mansion after his father's death, Walker comes across a ledger from 1936, which lists the names and earnings of pickers that season.

Among them is Mary Coin, who, he notes, earned much more than the others, though it is unlikely she could outpick a taller, sturdier able-bodied man. She is a mystery he resigns himself to not solving, after a frustrating non-conversation with her only surviving son.

Mary is, of course, the center and most interesting of the three characters. But we can't get close to her until the last chapter, where something of her stubbornness, composure and sly intelligence comes out.

The author wisely doesn't try to probe her personality and inner life, if she even had time for one, during her hardscrabble years.

Brigitte Frase is a book critic in Minneapolis.