Fifteen-year-old Kambili lives in luxury in Enugu, Nigeria. Kambili, her seventeen-year-old brother Jaja, and their parents—Papa and Mama—inhabit a huge house inside a walled compound. A chauffeur drives Kambili and Jaja to and from their private schools. Papa, Eugene Achike, is a wealthy and famous factory owner, newspaper publisher, philanthropist, and champion of human rights. Papa and Mama are pillars of St. Agnes.

In the privacy of his own home, however, Papa is an abusive tyrant. He demands perfection from Jaja and Kambili, plans every moment of their lives, and punishes them physically if they don’t follow his plan. Kevin, their chauffeur, takes them everywhere and reports their behavior to Papa. Papa also physically abuses Mama, who excuses and endures his abuse by taking refuge in her collection of miniature figurines of ballet dancers.

A military coup topples the government, and Papa gets caught up in pro-democracy work. At about the same time, Mama discovers she is pregnant again after several miscarriages. Early in her pregnancy, on Pentecost Sunday, Mama feels ill and asks to be excused from a social obligation. Papa beats her so badly for this that she miscarries again. Kambili and Jaja watch as Papa carries Mama out of the house.

Mama comes home from the hospital, and Kambili’s life resumes its strict routine. But she struggles in school and comes in second, not her usual first, on her exams. When he hears of this, Papa becomes furious, but an emergency interrupts Kambili’s punishment. The military government arrests Ade Coker, the editor of Papa’s newspaper. After arranging Ade Coker’s release, Papa turns his attention back to Kambili and reminds her that god expects perfection.

As is the custom in Nigeria, the Achike family returns to their home village, Abba, for Christmas. At their country mansion in Abba, Papa receives an endless stream of villagers and bestows gifts on them, while Mama and the other women feed the visitors. Papa’s father, Papa-Nnukwu, also lives in Abba. Papa allows Kambili and Jaja to visit Papa-Nnukwu, but only for fifteen minutes because he views their grandfather as a heathen.

Aunty Ifeoma, Papa’s sister, arrives in Abba with her three children: Amaka, a fifteen-year-old girl; Obiora, a slightly younger boy; and Chima, a boy of seven. Against Papa’s wishes and without his knowledge, Aunty Ifeoma takes Kambili and Jaja to a traditional festival. Even worse, she brings Papa-Nnukwu along. Papa-Nnukwu explains Igbo folklore to his grandchildren. Later, when Aunty Ifeoma also asks Papa to let Kambili and Jaja come with her on a pilgrimage to a Catholic shrine, Papa reluctantly agrees.

Kevin drives Kambili and Jaja to visit Aunt Ifeoma in Nsukka, where she lectures at the university. Her small flat lacks luxuries they are used to. The electricity and water are unreliable. Gas and food are scarce. But laughter and music fill Aunty Ifeoma’s house. Aunty Ifeoma lets children speak their minds without fear of punishment. They listen to popular music and watch television. Jaja thrives in this new environment and takes up Aunty Ifeoma’s enthusiasm for her rare purple hibiscus and the other flowers in her colorful garden. Kambili adjusts less easily. She must learn the simplest household tasks, and her cousin, Amaka, sneers at her for being rich. Kambili acts shy and nervous. Father Amadi, a handsome young priest, tries to bring Kambili out of her shell. He encourages her to run, sing, and smile.

Police once more arrest Ade Coker, so Papa asks Aunty Ifeoma to let Kambili and Jaja stay in Nsukka for a few days more. Then Papa-Nnukwu gets sick, and Aunty Ifeoma brings him to stay with her in Nsukka. While helping take care of Papa-Nnukwu, Kambili and Jaja get to know him and hear his stories. When Papa discovers that his “heathen” father is living under the same roof as his children, he travels to Aunty Ifeoma’s to take them back home. However, Papa arrives in Nsukka right after Papa-Nnukwu dies, and Papa then berates Aunty Ifeoma for not calling a priest. Back home in Enugu, Kambili and Jaja see their Mama’s swollen face and black eye. After dinner, Papa punishes them for not telling him about Papa-Nnukwu, and he forces Kambili to stand in boiling water.

Later, Kambili and Jaja show each other their secret souvenirs from Nsukka. Kambili has a watercolor portrait of Papa-Nnukwu, painted by Amaka. Jaja has cuttings from Aunty Ifeoma’s purple hibiscus plants. They keep their secrets as the political situation worsens and Papa becomes ever more tense. Leaders of the pro-democracy movement warn Papa that he is in danger. A pipe bomb kills Ade Coker.

One day, Papa discovers the portrait of Papa-Nnukwu and erupts in rage. He kicks Kambili until she falls unconscious. After Kambili gets out of the hospital, she and Jaja go back to Nsukka to stay with Aunty Ifeoma. Kambili spends more time with Father Amadi, with whom she is now in love. Mama arrives unexpectedly in a taxi. Once again, Papa has beaten her and caused her to miscarry. In spite of Aunty Ifeoma’s outrage, Mama goes back home, taking Kambili and Jaja with her.

The day after Mama, Jaja, and Kambili return home is Palm Sunday. Jaja refuses to take communion at Mass. After church, Papa explodes in rage and throws a heavy liturgical book at Jaja. Instead of hitting Jaja, however, the book hits Mama’s precious figurines and shatters them into bits. From that moment on, everything changes. Papa seems to shrink as Jaja continues to defy him. Aunty Ifeoma loses her university job and applies for a visa so she can go to America. Father Amadi gets a new assignment in Germany.

Papa dies suddenly. The autopsy reveals he has been poisoned. Mama tells Kambili and Jaja that she’d been feeding Papa poison, but when the police arrive, Jaja confesses to the crime. Mama spends a small fortune on lawyers and bribes to ease Jaja’s time in jail. Meanwhile, the Head of State dies, and pro-democracy groups accuse the military regime of killing Papa. Finally, after more than thirty months, Mama and Kambili learn that Jaja will be released. They begin to plan a better future.