The TARDIS lands on an unknown green planet. Gillian is frightened by an unknown, ugly cat-like animal and John chases it off with a rock. Large rocks fall from above and damage the door of the TARDIS, leaving it unable to close and thus the TARDIS is unable to move. A giant bird captures John and Gillian and imprisons them in a cage with a pair of primate-like animals. At the bird's nest, they are prodded by smaller birds and dislike the food and drink provided them. The Doctor arrives with the cat-like animal, who chews through the cage, allowing John and Gillian to escape. Before they leave in the TARDIS, John vows to never be unkind to an animal again.