The novel deals with the rise and fall of Okonkwo , a man from the village of Unuofia. Okonkwo was not born a great man, but he achieved success by his hard work. His father was a lazy man who preferred playing the flute to tending the soil. Okonkwo was opposed to his father's way of life, and always feared failure. In order to prove his ability, he had overthrown the greatest wrestler in nine villages, set himself up with three wives, two barns filled with yams and a reputation for being a hard worker. The reader learns that he was also one of the egwugwu--the masked spirits of the ancestors. His importance is proved when he is sent as an emissary to Mbaino in order to negotiate for hostages, and he returns successfully with a boy, Ikemefuna and a virgin.

Okonkwo has his faults, one of them being his impatience of less successful men and secondly his pride over his own status. His stern exterior conceals a love for Ikemefuna, who lives with him; an anxiety over his son Nwoye, who seems to take after his father; and an adoration for his daughter Ezinma. His fiery temperament leads to beating his second wife during the Week of Peace. He even shoots at her with his gun, but luckily he misses. This shows his short temper and a tendency to act on impulse, a tendency that backfires on him later on in the novel. The boy, Ikemefuna, is ordered to death by the Oracle of the Hills and Caves. Though Okonkwo is upset, he shows his fearlessness and impartiality by slaying the boy himself. His final fault against his tribe is when he unintentionally shoots a boy and kills him; for this he is banished from the village for seven years and has to live in his mother's village of Mbanta. This is a great disappointment for him although he is consoled and encouraged by his uncle, Uchendu.

The reader now hears of the arrival of the Christian missionaries, who take over the village of Mbanta, as well as Umuofia, set up a church and proceed to convert the tribesmen to Christianity. At first, they face much resistence, but gradually many of the tribesmen including Okonkwo's own son, Nwoye, are converted and follow the path of Christ. After his period of exile, Okonkwo returns to Umuofia with his family and finds it totally changed. The missionaries have done a lot for the village. Umuofia is prospering economically, but Okonkwo is firm in his refusal to charge his religion.

The missionary Mr. Brown is overzealous in his methods. A Christian named Enoch enters a meeting of the tribe in which the egwugwu is present, and he unmasks one of them. This causes great anger, and the villagers make a decision to destroy the church, which they eventually do. This action incites the wrath of the District Commissioner, who invites Okonkwo along with five other men and overpowers and imprisons them. These elders are humiliated in the prison. On their return, another meeting is held. The commissioner sends some men to stop the proceedings, and Okonkwo, in a fit of fury, beheads one of them. The tribe is disturbed and they let the other men escape. Finding no more support from his tribesmen, Okonkwo hangs himself. His world has fallen apart.

His tribesmen even refuse to cut him down and bury him since taking one's own life is a violation of the earth goddess, and his men would not bury such a man. His friend Obierika's words describe the tragedy most powerfully That man was one of the greatest men in Umuofia. You drove him to kill himself; and now he will be buried like a dog.

Okonkwo's suicide is symbolic of the self-destruction of the tribe, for he was a symbol of the power and pride that the tribe had and with its demise, the tribe's moral center and structure gave way to a more dominant one. With his death, the old way of life is gone forever.