As the trio travel near a remote village, two of the human slaves living ther, Stern and Lang, make their escape. Virdon and Burke are captured by gorillas searching for the slaves. When the gorilla prefect learns their true identity he plans to hang them. At the last moment, Galen, Stern and Lang blow up the village armoury, free the astronauts, and start a revolution to drive the gorillas out. While the three friends continue on their travels, the freed humans flee to the mountains to build a new settlement.