the narrator and main character is kariuki, a young kenyan boy living under the oppressive rule of a british plantation owner named bwama ruin. while near a watering hole, kariuki meets bwama's nephew nigel, who is fishing. nigel is a white boy from britain staying in kenya for the summer. he is one year younger than kariuki and is unaware of the systematic oppression of the kenyan people. kariuki and nigel quickly become friends. nigel quickly gains the title of “the mzungu boy”, meaning "white boy", by the older boys of the village. nigel immediately falls in love with hunting on the prairies of africa. he especially enjoys hunting old moses, which according to kariuki is the oldest, toughest warthog in the world. kariuki's older brother hari is part of the mau mau rebellion. during one of nigel's and kariuki's hunting expeditions, they get separated. bwama ruin calls in the british army to search for nigel. when kariuki goes to search for nigel, he finds him captured by the mau mau. kariuki frees nigel but while they try to escape, they both get captured by the mau mau. although the mau mau want to kill them both, kariuki's brother hari frees them. nigel and kariuki run back to the town while the mau mau attempt to flee from the british soldiers by hiding in the mountains. when the boys get back to the plantation, they go to bwama ruin's estate to find that british soldiers have found and killed hari as he tried to flee with the mau mau rebels. kariuki runs out of the town overcome with emotion; the book ends with nigel, "the mzungo boy", finding and comforting kariuki.