Aminata Diallo, from the village of Bayo, in western Africa, is the daughter of Mamadu, a jeweler, and Sira, a midwife. At the age of eleven, she is kidnapped after watching her parents murdered and her village burned. She is captured by African slave traders, who sell her to white slave traders. She and the other captives are marched in a coffle, a line of prisoners chained together, on a harrowing three-month journey to the coast. During this ordeal, she vows to return to her village one day. After being branded, the captives are loaded onto a ship that crosses the Atlantic. A young African boy named Chekura, who has been working for the slave traders, is betrayed by them and also enslaved. He becomes Aminata’s ally and friend.

Conditions aboard the ship are barbaric. Aminata survives because she is young, strong, and determined. She also has special skills. She works as a translator for the whites and is allowed to sleep separately from the others. She witnesses the ship’s doctor raping the other women, and she survives a slave revolt. After arriving in South Carolina, she is sold to an indigo planter named Appleby. Her name is anglicized to Meena Dee, and she is taken under the wing of a wise female slave named Georgia, a South Carolina native who teaches her to speak English. Georgia also takes Aminata along when she delivers babies, just as her mother had done. A fellow Muslim slave, Mamed, who is half-white, recognizes her potential and teaches her to read and write, a dream of hers since her father first taught her some Arabic letters.

One day, Chekura appears—he has found her through “the fishnet” (121), a secret message conduit for enslaved people to locate relatives and friends. When Appleby hears about the visits, he rapes Aminata. Despite this horrific act, Aminata and Chekura marry and conceive a baby. When Appleby hears about the baby he brutally punishes her in front of all the other slaves. She gives birth to a little boy, whom she names Mamadu, after her father. After ten months, Appleby takes her baby away and sells him. Despondent, she refuses to work anymore, despite repeated beatings, so he sells her to a man named Solomon Lindo, in Charles Town (the former name of Charleston).

Lindo is an indigo inspector. He first met Aminata months ago, while inspecting Appleby’s plantation. Impressed by her intelligence, he offers to buy Aminata, but Appleby refuses. Now, he and his wife are kind to her, and teach her accounting. Mrs. Lindo buys her books and Aminata works as a midwife, and is required to give part of her earnings to Lindo. She delivers Lindo’s son David, but a few years later, a smallpox epidemic breaks out, killing the child and his mother. Shortly thereafter, Chekura reappears. He was sold at the same time she was, and he never heard about Mamadu being taken from her. As soon as he was able, he made his way north. He tells his wife that their baby died. He also reveals that Lindo assisted Appleby in selling the child. Aminata’s trust in Lindo is shattered, but when she confronts him, he denies the accusation.

In order to win back her trust, Lindo brings her with him to New York City, where he will try to rally the Governor for help with the indigo trade, which is now depressed. She will be in charge of his correspondence and his accounts. In New York, Aminata meets Sam Fraunces, a famed black tavern owner. With his help, she is able to escape from Lindo. Her escape is made easier because rioting has overtaken the city at the outbreak of the Revolutionary War. She lives in Canvas Town, where free and escaped blacks live in shacks as they try to earn a living. She makes her name as a midwife and a teacher of blacks who wish to learn how to read. Because of her talents, she is recruited by the British to help assemble all the Black Loyalists. Any black person who has served on the British side in the War will have his or her name listed in The Book of Negroes, an actual historical document from this time period.

Aminata acts as a scribe and translator, entering names in the Book. As long as they can prove one year of service to the British, the latter have pledged to take them to the British Canadian colony of Nova Scotia. One day, Chekura appears. He is now free, and she arranges for her husband to accompany her to Nova Scotia. She becomes pregnant again, and just as they are about to board the ship, Aminata is detained: there is a warrant out for her arrest as a runaway slave. Expecting to see Lindo, it is instead Appleby who appears in court. But just in time to save his friend, Sam Fraunces tracks down Lindo, who appears and swears she is his property. He then sets her free. He explains that Appleby was determined to take her baby away, so he made sure Mamadu was with a kind owner. Aminata, now a free woman, finds another ship to Nova Scotia, hoping to be reunited with her husband.

Aminata arrives in Shelbourne, Nova Scotia penniless and pregnant. She is befriended by Theo McArdle, a printer who gives her a job. She meets Daddy Moses and other free blacks who live in Birchtown, and makes her home among them. She teaches free blacks to read and also earns money as a midwife. When she gives birth to her daughter, May, she takes the baby to work with her in the print shop. It is her that she meets the Witherspoons, wealthy whites in the whaling business. She works five days a week for the couple, who dote upon May. She tries many times to find Chekura, but is unsuccessful.

When the economy of Shelbourne goes downhill, tensions rise between whites and blacks. Riots break out, as mobs of white men kill and rape the free blacks, and then attack Birchtown. In the chaos, May is abducted by the Witherspoons, and Aminata is desolate. She meets a passionate black man named Thomas Henry who talks of returning to Africa, but no one pays attention until a young British naval officer named John Clarkson comes to Nova Scotia with the same message. The Sierra Leone Company, run by dedicated abolitionists, will finance a mass migration to Africa. Aminata will help get them ready, but is determined to stay in case Chekura returns or May is found. But when Clarkson finds out that her husband’s ship went down, Aminata joins the exodus to Africa.

In Sierra Leone, the Company has purchased land from local traders, and the colony of Freetown is established. But despite Clarkson’s best efforts, history repeats itself. The stain of the slavery is everywhere, and Freetown is the only safe zone. Aminata and the others know that Bance Island, where she was first traded into captivity, is just a few miles away. Tensions between the colonists and the Company accelerate as the free blacks realize they are not receiving all that was promised to them.

Aminata now wishes only to return to her village, and though Clarkson tries to dissuade her, she gets help from an abolitionist named Falconbridge. He arranges for her to travel inland with a wily African trader named Alassane, whom pays to take her to Bayo. She learns that he intends to sell her, which she overhears one night, during their long journey inland. She escapes during the night, sick with a fever, and is rescued by villagers, who get her back to Freetown.

The novel closes with Aminata sailing to England to take up Clarkson on his offer to help the abolitionists. It is her final ocean voyage, and she is dedicated to their cause. They ask her to testify before Parliament, after which she becomes famous all over London. One day, soon after she meets the King and Queen of England, she has a visitor. It is her now eighteen-year old daughter, May, who has been searching for her. May had been working as a servant in London and managed to escape from the Witherspoons. Now, she is a teacher in a black school. May and her mother share their stories and try to make up for all the lost years. May is proud of her mother and follows in her footsteps as a strong, determined woman. She is now engaged to a good man, a publisher who will publish Aminata’s memoirs. May cares for her mother until her dying day.