The protagonist Cora’s grandmother, Ajarry, is kidnapped from Africa as a child and brought to America, where she is sold many times before ending up on Randall plantation. Ajarry has three husbands and five children, and the only one of the children that survives is Mabel, Cora’s mother. Ajarry dies of a brain hemorrhage while working in the cotton field.
The narrative jumps to Cora’s adolescence—she is still living on Randall. Cora spends every Sunday tending to her garden, which she inherited from Mabel (who inherited it from Ajarry). After Mabel ran away, Cora became a “stray” and was placed in Hob, the cabin for “wretched” women. Soon after Cora was placed there, she had a confrontation with a man named Blake who built a wooden house for his dog in Cora’s garden. Cora destroyed the doghouse with a hatchet and cut off the dog’s tail. Soon after, she was gang-raped by four enslaved men.
One day, the enslaved population on Randall is preparing a birthday feast for Jockey, an enslaved man who picks random days on which to celebrate his birthday. Before the feast, Cora talks to her friend Lovey, a kind and simple young woman who—unlike Cora—enjoys dancing. Just before the feast, a young man named Caesar pulls Cora aside and asks her to run away with him, an idea Cora dismisses as ludicrous. After the feast, the slaves dance and play music, but they’re interrupted by James and Terrance Randall, the brothers who own the plantation. The brothers force the slaves to dance for their entertainment and Terrance grows furious when a young boy, Chester, accidentally knocks wine onto Terrance’s shirt. As Terrance is about to hit Chester, Cora defends him, and both of them are brutally whipped as a result.
Soon after Jockey’s feast, James Randall dies of kidney failure, which means that Terrance (the crueler brother) takes over the whole plantation. This causes a man named Big Anthony to run away, though Big Anthony is soon captured and tortured to death over a gruesome three-day period. After this, Cora agrees to run away with Caesar; he tells her that he is being assisted by Fletcher, a local shopkeeper who works for the underground railroad. The two set off in the night, and they soon realize that they are being followed by Lovey. They do not get far from the plantation before running into hog farmers who manage to capture Lovey. Cora is tackled by a young boy and she kills him with a rock. After Cora and Caesar find Fletcher, Fletcher introduces them to Lumbly, who houses an underground railroad station beneath his farm. They travel in a rickety car to South Carolina.
When Mabel disappeared, she gave no indication to Cora that she was leaving. Old Randall hired Ridgeway, a notorious slave catcher, to find Mabel, but he was unable to do so. Ridgeway is the son of a blacksmith, Ridgeway Sr. who believed in a “Great Spirit” uniting all living things. As a teenager, Ridgeway becomes a patroller, terrorizing and abusing black people, before deciding to become a professional slave catcher. Ridgeway is tortured by his failure to capture Mabel and he swears he will track down Cora in her place.
Mr. and Mrs. Anderson are a couple living in South Carolina with their two children, who are cared for by a black nanny called Bessie. Bessie sometimes takes the children to visit their father at his office in the Griffin Building, a 12-story building with an elevator. Bessie lives in dormitories supervised by white proctors, including Miss Lucy. It is eventually revealed that Bessie is, in fact, Cora, who (along with Caesar) assumed a fake identity in South Carolina with the assistance of a white saloon owner and underground railroad agent named Sam. Cora takes classes in literacy with Miss Handler, and she undergoes medical examinations at the local hospital. One night, there is a dormitory social at which Cora wears a pretty new dress and chats happily with Caesar. Although there is an underground railroad train coming in a few days, they decide to stay in South Carolina. Later that night, Cora sees a black woman running through the green in front of the dormitories screaming, “They’re taking away my babies!” This image haunts Cora.
Soon, Cora is given a new job as a “type” in a museum. She poses in three different scenes representing different stages in the transatlantic slave trade: “Scenes from Darkest Africa,” “Life on the Slave Ship,” and “Typical Day on the Plantation.” At her next medical examination, Dr. Stevens suggests that Cora undergo sterilization, which horrifies her. Soon after, Sam informs her and Caesar that there are rumors that the doctors are not treating some of the black dormitory residents for syphilis so that the doctors can study the infection’s progression. Meanwhile, other residents are being forcibly sterilized in order to cull the black population. Shortly after, Cora has an interaction with Miss Lucy that causes her to fear that her true identity as a runaway slave may have been revealed. She goes to warn Sam, who tells Cora that Ridgeway is after her and hides her down on the underground railroad platform. After waiting in the dark, Cora realizes that on the other side of the door Sam’s house is on fire.
Cora is brought to North Carolina by a teenage engineer on the underground railroad. Once there, Martin Wells discovers her on the platform and he is alarmed by her arrival, as the station is supposed to be closed. Martin shows Cora the Freedom Trail, a seemingly endless line of lynched black bodies left hanging on display, and he explains that black people are not allowed in North Carolina anymore. Martin lives with his wife, Ethel, and they hide Cora in their attic. They have a servant, Fiona, a young Irish woman who cannot know about Cora’s presence, lest she alert others and get Cora, Martin, and Ethel killed. Through a crack in the attic wall, Cora watches the Friday Festival, an event at which the local townspeople watch a minstrel show and then publically lynch a black person. The heat in the attic is so intense that Cora sometimes passes out, and she is given only very small amounts of water and food. She eventually gets sick, and Ethel cares for her, which marks a shift from Ethel’s previously hostile attitude. Soon after, patrollers arrive at the house and storm straight up to the attic. Among them is Ridgeway, who grabs Cora by the ankles and throws her down the stairs. Ridgeway takes Cora with him. As they drive away Martin and Ethel are stoned to death by the townspeople.
Cora travels through Tennessee with Ridgeway, Ridgeway’s accomplices Homer and Boseman, and a captured runaway, Jasper, who won’t stop singing hymns. Homer is a 10-year-old black boy who serves as Ridgeway’s driver and bookkeeper. Although he is technically free, Homer mysteriously decides to stay with Ridgeway and he even voluntarily chains himself to Ridgeway’s wagon at night. Boseman, meanwhile, has been traveling with Ridgeway for three years and he wears a necklace of shriveled ears. Ridgeway eventually gets irritated by Jasper’s singing and shoots him. They travel through towns struck by wildfires and yellow fever. One evening, Ridgeway gives Cora a new dress to wear and takes her out for dinner. He informs Cora that Caesar was killed by a mob in South Carolina. After the dinner, Boseman attempts to rape Cora but is interrupted by Royal, Justin, and Red, three free black men who shoot Boseman and rescue Cora. Cora kicks Ridgway three times in the face before fleeing.
The narrative jumps into the future, with Cora now living on Valentine farm, a free black community in Indiana. She is once again taking classes, and she shares a cabin with a woman named Sybil and Sybil’s daughter, Molly, with whom Cora has an affectionate bond. The farm is run by John Valentine, a white-passing freeborn black man, and his wife, Gloria. Visitors often come to the farm, including abolitionists, musicians, and poets. Cora, meanwhile, is being courted by Royal, who shows her a nearby underground railroad station. Cora spends most of her time in the farm’s library, and one day John joins her there to discuss the future of the farm. The residents are about to debate whether the community should move west or stay put and expel the runaways who live there. John tells Cora that he feels a sense of duty to help all black people, who he believes must look out for one another.
The farm hosts a debate about the community’s future at which all residents are present. One of the oldest residents, Mingo, gives a speech advocating the expulsion of runaways and “criminals” and arguing that the only way to achieve “Negro uplift” is through embracing only the “best” members of the race. Elijah Lander, a biracial abolitionist and rhetorician, gives the next speech. Lander argues that Valentine farm may be a “delusion,” but it is a delusion that its residents must believe in. Just as Lander’s speech is coming to an end, the meeting is disrupted by Ridgeway and a gang of white men. They shoot Lander and Royal and drag off many others. Royal dies in Cora’s arms while telling her with a smile to escape via the underground railroad. Ridgeway captures Cora and demands that she lead him to the railroad station.
The penultimate chapter describes Mabel’s life and her decision to run away. When Cora was born, Mabel was repeatedly raped by Moses, one of the black bosses on Randall. Cora had been born as a result of Mabel’s romantic affair, at the age of fourteen, with Grayson, a kind and confident man who died of fever before learning that Mabel was pregnant. When Mabel runs away, she is thrilled by the taste of freedom but she immediately decides that she must go back for Cora. However, on her way back to Randall she is bitten by a snake and dies, her body swallowed up by the swamp.
Cora takes Ridgeway and Homer to the station. Just as they get to the stairs, though, Cora pulls her chains around Ridgway’s neck, which causes him to fall down the stairs. As he lies dying from his injuries, Ridgeway asks that Homer write down his last words. Cora, meanwhile, steps onto the handcar waiting in the station and begins slowly conveying herself to freedom, swinging at the tunnel with a pickax as she goes. After a while she grows too tired and, in between sleeps, continues her journey on foot. Eventually, she reaches the mouth of the tunnel and she can tell from the sun that she has made it north. She encounters a group of wagon drivers and sits up with an elderly black man named Ollie, who offers her food and water and suggests that they catch up on each other’s stories.