The documentary "Brotherhood of Lions" follows three lionesses and their nine cubs in Kenya's Masai Mara reserve. The film follows the cubs' journey to adulthood over five years. The young males form a coalition to work together against rivals, but first, they must leave their mothers at two years old and fend for themselves.

The documentary introduces the five male lions, named by the Masai people, and shows their distinct personalities. In spring 2021, the lions' mothers arrive with new cubs, and the 13 lions form a loose grouping to hunt together. However, the older lions' urge to reproduce conflicts with the interests of the mothers and their sons. Hunger takes them across the Rongai River, where they must avoid other prides. The film showcases the lions' fascination with their new surroundings and their struggle to hunt in unfamiliar regions.