The book opens as Nnu Ego runs away from her home in Lagos, Nigeria, where her first baby has just died. She has decided to commit suicide.
The story flashes back to the story of how Nnu Ego was conceived. Her father, Agbadi, though he has many wives, is in love with a proud and haughty young woman named Ona. Ona refuses to marry him because she is obligated to produce a son for her father's family line, and not a husband's. But when Agbadi is almost killed in a hunting accident, Ona nurses him back to health and becomes pregnant with his child. She agrees that if it's a daughter, the child will belong to Agbadi.
Nnu Ego is Agbadi's favorite daughter and she grows into a beautiful young woman. Her first marriage is to the son of another wealthy and titled family. Unfortunately, the marriage soon grows sour because Nnu Ego fails to have children. Her husband takes a second wife, who quickly conceives. Nnu Ego grows thin and worn out because she's so unhappy. She goes back to live with her father, who arranges a second marriage.
Nnu Ego's second marriage is to Nnaife, a man who works in Lagos as the washer for a white family, Dr. and Mrs. Meers. Though Nnu Ego is disappointed with Nnaife – he isn't her ideal man – she quickly becomes pregnant. This is the child that dies and propels her to almost commit suicide by jumping off a bridge.
When she's talked out of jumping off the bridge, Nnu Ego returns home and becomes pregnant again rather quickly. World War II interferes in Nnu Ego's and Nnaife's happiness. The Meers return to Europe, and Nnaife is out of work for months while Nnu Ego supports the family through petty trade. Nnaife eventually gets work on a ship, which means he's gone for months at a time. Nnu Ego struggles to make ends meet while he's gone. When he finally returns, it's only to be greeted by the news that his elder brother has died and Nnaife has inherited all his brother's wives and children. Most of the wives remain in Ibuza, but Adaku comes to Lagos and moves in with Nnu Ego and Nnaife.
Nnu Ego learns to become the senior wife, and to share Nnaife's pitiful salary with Adaku and her children. Life is a constant struggle for survival, but it only gets worse when Nnaife is conscripted into the army and sent to fight in World War II. He's gone for four years. His wives must wait patiently with no news and no salary.
Adaku takes up trading to support herself and her two children, while Nnu Ego struggles to support her four children. Nnu Ego goes home to Ibuza because her father dies. During her long absence, Adaku's trading becomes very successful, while Nnu Ego's dwindles to nothing. Nnu Ego has to start all over again, but she is jealous of Adaku's success. The two women have a conflict, and the family men settle in favor of Nnu Ego even though she's wrong. It turns out that the men side with Nnu Ego because she is the senior wife. Adaku finally recognizes that because she is the junior wife and has only has daughters, her position in the family is nothing. She leaves to become a prostitute.
After many years, Nnu Ego discovers that she has been sent three years of Nnaife's salary. She is finally able to pay her children's school fees and feed them well. Nnaife arrives home not long after. The war is over. He apparently feels the sting of Adaku's defection because he decides to go home and assert his rights of inheritance with his brother's eldest wife, Adankwo. He gets her pregnant and brings home yet another wife, a young girl named Okpo.
Nnu Ego is frustrated. They can hardly afford the children they have, yet Nnaife keeps fathering more children and demanding more wives. Yet Okpo is a good girl, and has the same traditional values that Nnu Ego has, so their relationship is a good one, almost like that of a mother and daughter. Nnaife surprises everybody when he offers the rest of his military money to pay for Oshia's expensive schooling. (Oshia is Nnaife and Nnu Ego's second child , but the first to live.) The expectation is that Oshia will graduate and get a good job and help pay for his younger brothers' schooling, as well as provide for his parents in their old age.
Oshia has other ideas, however. He wants to continue with university in America. His disregard for his own duties as the first-born son causes his parents great anguish. Nnaife is never the same again after he feels betrayed by Oshia. When his daughter, Kehinde, breaks his rules by running away with a Yoruba man, he assaults the father of Kehinde's husband. Sent to prison, Nnaife blames Nnu Ego for all his problems. Whatever love he once hand for her has turned to bitter hatred.
With Oshia in America, and Adim (Nnaife and Nnu Ego's third child and second living son) working and paying for his own schooling, and her two oldest daughters settled in marriages, Nnu Ego moves back to Ibuza. She is not welcome on Nnaife's family's compound so she moves into her father's old household with her youngest children. She lives out the rest of her days there.
When she dies, her children finally come home – Oshia from America and Adim from Canada – and throw her an expensive funeral. They build a shrine so that her descendants can pray to her and ask for children. But Nnu Ego refuses to answer those prayers.