"The Agitators" tells the true story of three American women — an escaped slave, a politician's wife and a reluctant feminist — who navigated gale-force winds of reform and revolution and changed the course of history. Author Dorothy Wickenden, executive editor of the New Yorker, knows a thing or two about writing with grace and economy, and she seamlessly braids her subjects' stories together into a riveting book.

Frances Seward, wife of William Henry Seward, Lincoln's secretary of state, was a woman at war with herself: an ardent abolitionist who longed for nothing more than to stay close to home and with family. As her husband struggled to keep the Union together, Frances opposed his political compromises at almost every turn, but their bond survived separation, violence and tragedy.

Martha Coffin Wright was a mother of six with a wicked wit and a fire for equal rights. Her introvert tendencies were continually overruled by her convictions: Though "convention dictated most of the circumstances of her life, she liked breaking rules, and then explaining why she had no choice," Wickenden writes. A leader in the nascent women's movement, she harbored fugitive slaves, violating federal law and transforming her kitchen, "where she stored her washboards and made her mother's Nantucket corn pudding … into a place of political asylum."

Harriet Tubman endured a horrific childhood, fled her owners to freedom, then went back South to smuggle other slaves to freedom on the Underground Railroad. Once the war began, Tubman served as a Union spymaster, gathering intelligence from her network among the South's enslaved population. After the war, she fought wearying battles to sustain rights won by Blacks after the war's end.

Their lives converged in their hometown of Auburn, N.Y. (Seward helped Tubman buy a home there), where they became collaborators and devoted friends. While Tubman's mythic labors personify the courage of the anti-slavery struggle, Frances Seward's conflicted conscience embodies the anguish of a country longing for peace but moving toward war. Wickenden draws heavily from Frances' correspondence with Henry Seward, and her letters, by turn affectionate and anguished, are an eloquent testament to her divided soul.

Wickenden distills the violence that consumed the country before the Civil War, its bloody progress and the toxic political divisions in its aftermath. But she never loses her focus on her subjects. She weaves their stories together with gravity and humor in a narrative so tightly knit it reads like accomplished literary fiction. She describes abolitionist John Brown in a few words that say so much: "His crevassed face a topographical map of bitterness and resolve."

"The Agitators" will move you, and it will make you sad. So much of what convulsed the country in the 19th century remains with us: mob violence, virulent racism and an appalling disregard for human dignity. But there's another message: People of fierce and heartfelt principles can bend history to their will. If you're an agitator, even a quiet one, read this book.

Mary Ann Gwinn is a book critic in Seattle and past board member of the National Book Critics Circle.

The Agitators
By: Dorothy Wickenden.
Publisher: Scribner, 400 pages, $30.