The story in a nutshell: The pilgrims meet an old man mining his way through a mountain to, he says, make a tunnel to the other side. Taking pity on the man Tripitaka resolves that he and his disciples will help the man, no matter how long it takes. Monkey, quickly bored and wanting to continue the journey to India, uses magic to complete the tunnel quickly.
Tripitaka is angry at Monkey's laziness and banishes him. The old man turns out to be a demon, who was really mining the mountain to try and find a magic egg at its heart. He thinks the pilgrims have stolen the egg while he wasn't looking, so he captures them and is about to kill them when Monkey returns. He defeats the demon and makes it up with Tripitaka.