In 1959 an overzealous Baptist minister named Nathan Price drags his wife and four daughters deep into the heart of the Congo on a mission to save the unenlightened souls of Africa. The five women narrate the novel. From the outset, the attitudes of the five women cover a wide spectrum. The mother, Orleanna passively accepts the turn of events, as she passively accepts everything her husband tells her. Fifteen-year-old beauty queen Rachel resents her separation from normal teen life. Five year old adventurer Ruth May is both excited and frightened. Fourteen-year-old Leah, who alone shares her father's ardent religious faith, is enthusiastic. Leah's twin Adah a cripple and mute by birth, but also a brilliant observer, merely views the move, as she does all of life, with a wry and cynical detachment. One thing that the women share, however, is the unwavering faith that they are carrying with them a culture far superior to the one already existing in the village of Kilanga, and that they will therefore instantly be masters of their new domain.
It does not take long for this faith to begin to waver. The first sign that they have miscalculated the superiority of their way of life comes when Nathan attempts to plant a vegetable garden. His "demonstration garden" is intended to both provide food for his family, and to instruct the natives in simple agricultural principles that might save them from malnutrition. However, though his garden grows lush and huge, none of his plants ever bear fruit. It takes him several weeks to realize that his plants cannot bear fruit here, because there are no African pollinators suited to North American vegetables. The next, and much larger, blow comes when their live-in helper, Mama Tataba becomes so enraged at Nathan's insistence on baptism for the villagers that she deserts them. As Mama Tataba explains in her final burst of anger, the villagers will never agree to being dunked in the river because a crocodile recently ate a young girl in that very river.
Though the women are shaken by these events, and slowly affected by the culture around them, Nathan remains steadfast in his original goals. He refuses to give up the attempt to baptize the villagers, or to bend his will in any way. When the only English-speaking member of the village, the handsome young school teacher, Anatole, informs Nathan that the chief, Tata Ndu, looks askance at his proselytizing, and fears that a move toward Christianity will spell the moral decline of his people, Nathan becomes outraged and throws Anatole out of his house rather than trying to gather more insight from him into the traditional religious life of the village. Even when their situation becomes mortally dangerous, Nathan clings tenaciously to his mission. Though little progress is being made in Kilanga, tremendous shifts are taking place elsewhere in the Congo. As the Underdowns, the Price's contacts to the Mission League, inform them on a surprise visit, Belgium is about to give the country its independence; a popular election will be held to select the new ruler. The Underdowns warn the Prices that they must evacuate the country, as purges of all Westerners are expected to take place once independence is won. Though his wife and daughters plead with him to heed this suggestion, Nathan refuses. The day that the evacuation plane arrives, and Nathan forbids his family to board, Orleanna crawls into bed and finds herself unable or unwilling to get up.
For several weeks, Orleanna lies in bed, and the three older girls must find a way to feed and care for the family themselves. When Orleanna finally pulls herself together she is a changed woman. She speaks her mind to Nathan, instead of cowering before him, and she begins to search desperately for a way to get her daughters out of Africa. She attempts to bribe the mercenary pilot Eeben Axelroot to fly them home, but he refuses to work without cash up front.
In the meantime, Leah is slowly falling in love with the schoolteacher Anatole, and falling out of love with her father and his simplistic view of right and wrong, while Adah is falling in love with the subtle language of Lingala. Rachel must pretend to be engaged to Eeben Axelroot to avoid a pity proposal of marriage from Chief Ndu, and she too finds her way into slight, and self- serving, infatuation. Ruth May falls ill with malaria, and when she recovers she is a pale, shadowy version of her old self.
A dry spell hits Kilanga and the people begin to starve. They organize a tremendous hunt, and controversy breaks out over whether Leah, who has become an excellent marksman under her friend Nelson's direction, can partake. The issue is put to a vote, which goes in favor of Leah's participation. Chief Ndu and the village's religious leader Tata Kuvundu are outraged by the idea of a woman participating in the hunt. Tata Kuvundu ominously warns that because they have overturned the natural world order, the animals will turn on them. The next evening Anatole finds an evil sign outside of his hut, and awakes the following morning to find a poisonous mamba snake curled up beside his bed.
After the hunt, Nelson finds an evil sign outside of his home, which happens to be the Price's chicken coop, and begs to spend the night in their house. Nathan refuses his request, but the girls take pity on his whimpering and join him outside. Taking a cue from one of their father's sermons, they spread the ground with ash, hoping to catch the footprints of the person planting poisonous snakes in the homes of those connected to the Prices. The next morning, when they sneak out to the chicken coop, they see the six-toed footprints of Tata Kuvundu, as well as a green mamba snake lying in the corner. Nelson pokes the snake with a pole, and it slithers out the door and past them. However, on its way out, it bites Ruth May on the shoulder, and she dies before their eyes.
In the wake of Ruth May's death, Orleanna silently leads her daughters out of Kilanga. They walk along the road in torrential rains as far as Bulungu, but then Leah falls too ill with malaria to continue on. From Bulungu, Rachel is flown to Johannesburg, South Africa by Eeben Axelroot, Adah and Orleanna make their way to the Belgian embassy in Leopoldville, and then on to Georgia, and as Leah convalesces under Anatole's care she falls wholly in love and decides to remain in the Congo as his wife. Rachel goes on to marry three men, the last of whom leaves her a luxury hotel deep in the French Congo, which she spends the rest of her life happily running. Adah goes to medical school and becomes a successful epidemiologist, taking on science as her religion. Leah and Anatole have four sons and spend their lives working toward true independence and justice for African nations. Orleanna, finally, lives her life wracked with guilt, and begging for forgiveness from Ruth May. In the last section of the book, narrated by the dead Ruth May, this forgiveness is granted.