Cassie Logan, who is 9 years old, is walking to school with her siblings Stacey, Christopher-John, and Little Man in rural Mississippi. Cassie talks about the land on which the Logan family lives. It belonged to Harlan Granger, but he sold 200 acres of it in 1886 to cover his taxes during Reconstruction. Their grandfather bought two hundred acres in 1887, then another two hundred acres in 1918. After several miles of walking, T.J. Avery and his brother appear. The Avery family sharecrop on the Granger plantation. At school, Cassie and Little Man go to their classroom, where Cassie's teacher, Daisy Crocker, gives them their textbooks, worn-out, outdated castoffs from the white school with a chart that says only white kids used these books up until they were in bad condition, indicating their future uses are intended only for black students. Crocker meets with Cassie's mother, Mary, who calmly glues a piece of paper over the chart containing the racist indicator in all the books. She hands them back to a dumbstruck Crocker. That Saturday their father, David Logan, comes home from his railroad job in Louisiana, bringing with him L.T. Morrison to assist in planting, farming, protection and other jobs, as L.T. was fired from the railroad for a fight that was the white men's fault. Papa leaves the next day to catch a train.
The next week, Stacey and T.J. take an examination and T.J. creates cheat sheets that he gives to Stacey when he sees Mrs. Logan approaching. She finds the notes, accuses Stacey of cheating on the test and whips him in front of the class before failing him. After school, T.J. runs to the Wallace Store, which the Logans forbid their children from visiting due to the Wallace's causing much of the black people's troubles. Stacey follows T.J. and the others follow Stacey. Mr. Morrison finds them fighting and separates them. Instead of telling their mother, Morrison leaves Stacey to do it himself. Stacey tells his mom and she takes the children to visit the Berrys. Mr. Berry is badly burned and gruesomely disfigured. Mama explains that the Wallaces are responsible for this and she does not want them to ever go near the Wallace's store again.
The next day, Mama recruits people to boycott the Wallace's Store because they are the cause of most of the trouble between the blacks and the whites, and are alleged to be members of the "night men". Big Ma, Cassie's grandmother, takes Stacey, Cassie and T.J. to Strawberry, a nearby town, and sells her goods at the market there. After lunch they visit the office of Mr. Jamison, who is their white lawyer and the son of the man who sold them Harlan Granger's land. He is one of the few white people who treats black people equally. T.J. takes Cassie and Stacey to the Barnett Mercantile to purchase items his family needs. T.J. admires a pearl-handled revolver on display, and says he wants to own it. Mr. Barnett begins serving T.J., but when white customers comes in Mr. Barnett interrupts his business with T.J. to serve them. Cassie reminds Mr. Barnett that they have been waiting for an hour; he tells her in racist terms to continue waiting. Cassie begins yelling at Mr. Barnett. Stacey tells her to be quiet, but Mr. Barnett ejects them both from the store. Cassie accidentally bumps into Lillian Jean Simms on the sidewalk. Lillian Jean orders her to get down in the road and apologize. Cassie tries running, but Lillian Jean's father twists her arm and throws her onto the road and orders her to apologize by calling Lillian Jean Miss as though she were an adult. Big Ma reluctantly tells her to apologize. When they get home, they find their uncle Hammer Logan from Chicago is visiting with a shiny silver Packard. Cassie tells him what happened and Hammer drives away seeking revenge. Mama tells Stacey to get Mr. Morrison to stop Hammer. She is worried that Hammer will be lynched for attacking a white family, but she finds him alive and unharmed. Before going to church, Hammer gives Stacey an early Christmas present, a wool coat whose sleeves are too long. At church, T.J. persuades Stacey to give him the wool coat because its sleeves make it look "like a preacher's coat". Papa comes home for Christmas and is staying until spring. On Christmas night, Jeremy visits the Logans and gives them nuts and a handmade flute for Stacey. Papa warns Stacey to be careful about being friends with Jeremy, saying that he will change because the Simms are racist; Jeremy might become prejudiced too. The next day, Papa calls the children into the barn, whips them and tells them never to go to the Wallace store again. Time passes and Papa starts leading the boycott against the store. Mr. Jamison visits and Big Ma signs papers giving the land to Papa and Hammer. He also warns them to be careful, because they could lose their land if they continue their boycott. Mr. Granger asks for the land again, but Papa refuses. Hammer returns to Chicago.
Cassie makes "peace" with Lillian Jean, calling her "Miz" Lillian Jean and being her friend by carrying her books to and from school. As Lillian Jean begins trusting Cassie, she tells her all her secrets. Cassie later leads Lillian Jean into the woods, drops her books on the ground and starts beating her, forcing her to apologize for all the humiliation she inflicted on Cassie. Cassie threatens to reveal all of Lillian Jean's secrets if she tells anyone what happened. T.J. is caught cheating again and fails for another year. He tells Mr. Wallace about Mrs. Logan and how she does not teach from the county-issued textbooks because she believes they contain biased information, and tells about the boycott. Mr. Granger, Mr. Wallace and a school board member fire Mrs. Logan on charges of "teaching unapproved things". Stacey blames T.J., although he denies it was his fault. After his black friends shun him, T.J. begins hanging out with Melvin and R.W. Simms, brothers of the Logans' friend Jeremy, who manipulate T.J. and mock him behind his back. Papa, Mr. Morrison and Stacey go to Vicksburg; on their way back, they find one of the wagon wheels has been tampered with. As Papa fixes it they are ambushed by the Wallaces. Papa's leg is crushed when the started horse runs off. Mr. Morrison snaps the limbs of the Wallaces. Mr. Granger uses his banking influence to make the Logan's mortgage note due for full payment within a week even though the Logans had four more years to pay it. Uncle Hammer sells his car and other items, leaving the Logans able to pay the mortgage.
On the last night of church revival meetings in August, T.J. appears dressed up in gangster-like clothes with R.W. and Melvin in order to show his former friends he is better off without them. R.W. and Melvin take T.J. to get the pearl handled pistol at the Barnett store. The store is closed, but R.W. and Melvin convince T.J. to steal the gun while they rob the cash box. The Barnetts catch what appear to be three black burglars, as Melvin and R.W. are wearing stocking masks over their faces. R.W. hits Mr. Barnett with the flat end of an ax and slaps Mrs. Barnett, causing her to hit the back of her head on a stove and black out. They beat up T.J. when he threatens to reveal what happened. T.J. flees to the Logans. Stacey takes T.J. home before T.J.'s father finds him missing and kicks him out. The Simms and Wallaces attack the Avery's home, capture T.J. and are about to lynch him when Mr. Jameson and the town sheriff arrive. The Wallaces propose taking T.J. to the Logan's land and killing him and Papa and Mr. Morrison. The Logan children flee home where they are found to have been missing and reveal what happened. Papa and Mr. Morrison leave. Mama and Big Ma realize that there is a fire outside that may consume their land. The fire stops the lynching by causing the Simms, Wallaces and Logans to work together to extinguish it. Mrs. Barnett survives the burglary, but Mr. Barnett dies. The sheriff arrests T.J. and Cassie realizes that Papa set the fire to save T.J. Stacey asks what T.J.'s fate will be. Papa replies that he will be convicted of Mr. Barnett's murder and may be executed. Cassie, overwhelmed by the news, silently goes to bed. Although Cassie never liked T.J., she cries for him and the land.