After the Battle of Ball’s Bluff, John March, chaplain of the Union army, writes a letter from the battlefield to his wife, Margaret “Marmee,” and their daughters Meg, Jo, Beth, and Amy. The family lives in Concord, Massachusetts. Because of the atrocities March has witnessed, he exerts a certain self-censorship on his letters home. The brutality of war, including vultures eating the flesh of corpses and the horrors of the field hospital, are too brutal to be conveyed in letters read aloud to his innocent daughters. March had been in this part of the United States before, and he tells the following story.

It is twenty years earlier, and eighteen-year-old March is visiting Virginia as a peddler. For a while, he is a guest of a plantation owner, Augustus Clement. March meets Grace, an African American slave who nurses senile Mrs. Clement. March feels attracted to Grace, and with her help, he begins teaching a little slave girl to write, even though the law forbids teaching slaves to read and write. Soon, his teaching becomes known, and he is expelled from the plantation, but not before he witnesses Grace being brutally whipped.

After being expelled from the Clement plantation, young March makes a fortune as a peddler. Wealthy, he sells out his business and goes back home. He next becomes a preacher. When the Reverend Day invites him to go to Concord to preach, he meets the reverend’s sister, Margaret, or Marmee, a young woman with ideas of her own about women’s education.

Grace turns down the opportunity to leave the plantation to join the Union army as a nurse, unwilling to leave the dying Mr. Clement. March tries to persuade Grace, but she reveals to him that she is Mr. Clement’s daughter by a slave woman and feels morally obliged to stay and care for him until he dies. Though Clement had offers for selling her, he chose not to sell her to a brothel. The scars from the whippings made her undesirable for the brothel owners. Grace and March embrace passionately.

March is given a new destination in charge of organizing the freed slaves who have joined the Union army and are considered contraband goods. March learns that the real reason behind his dismissal is that someone accused him of having an affair with Grace. Though he regrets their embrace, nothing had happened between them. Ashamed and unable to tell his wife the truth, he writes to her that he is going to preach to the former slaves.

A young, enamored March decides to move to Concord to be closer to Marmee. He finds a job with a pencil-maker, whose son, Henry David Thoreau, reluctantly works while he dreams of leaving for the woods. March soon becomes friends with other local residents, including the Emersons. He discovers that Marmee is a strong abolitionist with a fierce temper and that she is involved in the Underground Railroad. One night, March meets Marmee in the woods, and they make love. They are quickly married a few weeks later. Their first daughter, Meg, is born nine months later.

March writes home again, describing his new post in a plantation run by Union forces and worked by free African Americans, whom he is to teach to write and read. Right after arriving, he discovers that although blacks are now free and free from beatings, they still are brutally punished. The plantation manager, Ethan Canning, imposes strict discipline on his workers, who complain that they had received better treatment in their old age and during their sicknesses from their old master.

The newlywed Marches lead a comfortable life in Concord, their happiness augmented by the birth of Jo. They are also active in the Underground Railroad, building a station in their own basement. Soon after, Beth is born. After attending a lecture by political agitator John Brown and seeing Marmee’s enthusiasm, March decides to invest heavily in Brown’s experiment, which leads March to bankruptcy by the time their fourth child, Amy, is born. They are forced to sell their house and move into a smaller one. Meg begins working as a governess, and Jo accepts a job as a paid companion to Aunt March.

March begins teaching his eager students, but he is appalled by the cruelty of the Union soldiers. As news reaches them that the army is withdrawing from the area, his students warn him to run off, but he decides to stay. The guerrillas appear at the plantation and shoot and maim Canning; then they come looking for March. March hides, and a man is killed in retaliation, leaving March guilty and remorseful. When the guerrillas begin to viciously attack the workers, March shows up. He and Canning are shot.

Marmee, accompanied by John Brooke, their neighbor’s tutor, goes to Washington, D.C., to nurse her convalescent husband, whom she finds almost unrecognizable and drifting in and out of consciousness. Marmee discovers Grace caressing her husband and jumps to the conclusion that Grace and her husband are lovers. Marmee confronts Grace, who tells her the whole story. Marmee is outraged that her husband did not tell her the true reasons for his new post.

When he regains consciousness, March does not want to be discharged on account of his poor health. On the contrary, he wants to go back to the battlefield and seek redemption. Beth becomes ill with scarlet fever, and Marmee goes back home. March feels guilty for having survived and thinks he does not deserve to return to his family. Grace urges him to go home and write sermons advocating for equality.

March gets home in time for Christmas. He knows he is not the same man he used to be, and he is haunted by memories of the dead. He realizes that he can learn to live with his memories.