In 1959, evangelical Baptist preacher Nathan Price takes his family to the Belgian Congo as missionaries. Nathan travels to Africa intent upon saving souls, but his wife, Orleanna, and four daughters (Rachel, Leah, Adah, and Ruth May) are more concerned with what supplies they should take to live comfortably there for the next year. When they arrive in the Congo, they are assigned to the village of Kilanga, where the Prices will be the only American family. Soon after their arrival, it becomes clear that they brought the wrong types of supplies and are woefully unprepared to deal with life in such a drastically different culture and climate. Nathan is inflexible in his approach to both the Congolese and his family, and Orleanna and her daughters are overwhelmed by their changed circumstances.
In time, the Price girls begin to adjust to their new life in the Congo. Rachel hates everything about it and simply wants to be a normal American teenager. Leah, Adah, and Ruth May, on the other hand, begin to appreciate the Congo. Leah, who is Adah's twin, enjoys observing the Congolese culture, while Adah studies the variety of plants, animals, and insects around them. Ruth May spends her time climbing trees and befriending the village children, to whom she teaches the game, "Mother, May I?" Meanwhile, Nathan tries to persuade the villagers to come to church and get baptized, and Orleanna worries for her family's safety and health.
The stability of the Prices' mission in Kilanga is soon challenged on both local and global fronts. One night Anatole, the schoolteacher, comes to dinner and tells the family that the village chief is unhappy with Nathan's church. Rather than trying to work out a compromise with the chief, Nathan gets angry and sends Anatole away. Around the same time, Ruth May breaks her arm, and Nathan takes her to a doctor in Stanleyville. While there, the doctor discusses the possibility of the Congo gaining independence, and Nathan scoffs at the idea. Soon after, the Underdowns (missionaries who once served in Kilanga) tell the Prices they need to leave the Congo due to the upcoming elections and independence, but Nathan refuses, determined to continue his mission.
