Galen leads his two friends to an enlightened village where his friend Landa is the female prefect. The village is almost deserted and Landa tells them that a huge space-craft, containing thirty humans led by Trang, appeared from the sky. The invaders proceeded to kill the village apes and plan to take over the planet and make the apes their slaves. Meanwhile Zaius and Urko argue about how best to fight this new threat. Pete and Alan go to an ancient armoury where they use gasoline make up molotov cocktails to fight the spacemen. They want to use Trang's ship to return to their own time but when he tries to escape they blow up the ship. After being much more successful against the invaders than the apes - armed with only rifles - had been, Zaius persuades Urko to let the trio escape - for now.