This is the account of the Great Depression I have been waiting for: detailed, personal, emotional and achingly intimate. To read it is to stand in the dark, peering into kitchen windows where families are broken, anxious and desperate.

In Canton, Ohio, eight days before Christmas 1933, four years into the Depression, hundreds of people found the energy and optimism to pick up pencils and pens and write to a mysterious man who offered them help.

A man calling himself B. Virdot ran an ad, no bigger than a playing card, in the town newspaper promising "financial aid" to those who described their circumstances in letters he promised would never be made public.

He kept his pledge, sending gifts of $5 apiece (when a pound of hamburger cost 11 cents) to 150 families, giving away the equivalent of $12,400 when his own future was not at all clear.

And he kept his secret, stashing those desperate letters in a small suitcase that survived his death, grew dusty in family attics and wound up, in the summer of 2008, in the hands of his grandson, Ted Gup.

It is our good fortune that Gup is a journalist, compelled not only by his family history but by what he calls "the extraordinary lives of 'ordinary people.'" He unfolds with care, as if it were a crumbling newspaper clipping, the story of his grandfather, Sam Stone, a men's clothier who took on an alias in the ad. He lied himself into security and ultimately success and then, Gup surmises, mined his harsh memories to fuel his compassion.

Gup pays the same tribute to the stories of those who secretly begged for help, letter writers who included fallen executives, abandoned wives and teenaged girls. One woman steamed open a used envelope, using its blank side to write on.

For these common folk he seeks to answer: How did they fall? Did the gift make a difference? What became of them and their descendents?

This is Gup's main theme: "It was the smallness of B. Virdot's gift ... that was its magic, not an act of governmental grandiosity but a gesture of human compassion. ... Its puniness and its purity ... gave it its transformative power, then and now. It was too small to put even a dent in the Great Depression but just enough to fend off the sense that no one cared and nothing could be done."

Families bought their kids shoes so they could go to school. They paid off debts to the milk man. They held onto an apartment, at least for another month.

We come to know Canton as if it were our own hometown, and its people as if they were our neighbors. By the final few chapters, though, some readers may find the tales repetitious. Gup's research is extraordinary, but he might have pared back his cast, letting the strongest stories stand taller.

Its epic sweep gives this book an ultimately hopeful tone, even for our own times, as reflected in one of Sam Stone's favorite sayings: "Each night I bury the record of today, for every morning a soul is born anew, and I do not permit the disappointments of today or yesterday to reflect on the possibilities of tomorrow."

Susan Ager, a longtime columnist for the Detroit Free Press, is at