Amos Fortune, a young African prince of a tribe called the At-mun-shi, lives a peaceful life until a raid on their village by slavers kills his father, the chief. At-mun is kidnapped and sold in New England. Now called 'Amos', he is sold to a man named Caleb Copeland, and though the Copeland family do not treat him badly he rejects his slave status and determines to earn his freedom. He comes to an arrangement with Copeland, but when Caleb dies in debt the arrangement is disregarded, and so Amos is sold again to a man named Diabolic Richardson. Richardson teaches Amos about tanning, and he becomes a skilled worker. He is now about thirty. Amos works for Richardson for four years, then buys his freedom. He marries a woman named Lily, whose freedom he also buys; but she dies a year later. Amos is sad that she died, yet happy she died a free person. Later he marries another African woman named Lydia, and it takes three more years to save up her freedom price. Lydia dies a year later. Again, Amos is sad she died but happy that she died free. He marries a younger woman named Violet, and he buys freedom for her daughter too. Amos moves to Jaffrey, New Hampshire to start his own tanning business there, and does so despite opposition. Eventually Amos saves up enough money that he buys his own land and he builds a house and a barn.
At one point Amos becomes very angry with his wife, who has taken money from him. He climbs a mountain and doesn't leave until he gets an answer from God. Eventually he receives his answer and climbs back down, then forgives his wife as she is sorry for stealing his money. She had done it to keep him from helping a woman named Lois who needed help to keep her children from being taken away. She was lazy and wouldn't support her children,but Amos had pity on her. He decides against helping her and keeps the money. Amos goes to buy the land that he has always wanted. They buy the land and they build a house before winter. They also build a place where Amos can work as a tanner. At this point in his life, he is 80 years old.
The book is based on the life of the real Amos Fortune, who was born free in Africa in 1710 and who died free in Jaffrey, New Hampshire, in 1801.