The pilgrims come to a village where a demon has been kidnapping children. The villagers are afraid the pilgrims are in league with the demon and set fire to the house where they stay to try and kill them. Monkey saves the rest of them but is badly burned himself, and his injuries are what prevents him from solving the plot in 5 minutes flat.
Upon learning that the demon has the form of a beautiful woman, Pigsy immediately rushes off to look for her. He meets her and they fight, but only when Sandy arrives to help can they overcome her together. They take her captive back to the village, where the villagers intend to execute her for all the children she has stolen and killed.
Tripitaka learns that she has been feeding the kidnapped children to her own son, and has pity for her, so releases her from her cell so she can see her son one more time to say goodbye to him. Tripitaka trusts that the demon will do the decent thing and return to face execution, but nobody else thinks this and the villagers intend to execute Tripitaka in her place.
Pigsy and Sandy are with the villagers at first, but when they learn she has a child they too pity her, and - independently - disguise themselves as the demon so they can save both the demon and Tripitaka. But when two demons arrive at the place of execution they end up revealing each other.
We now see evidence that backs up the theory of why this episode might have been deemed unsuitable for broadcast in 1980 - Tripitaka, Pigsy and Sandy are all lined up at a gallows, with ropes around their necks ready to be hanged.
Of course they are saved at the last minute when the demon returns. Monkey arrives on the scene with the dead childrens' skulls, and while at first it looks as though he is trying to shock away pity for the demon, in actual fact his plan is for her to use her magic to bring the children back to life. She does, and is redeemed by doing this.
Sounds like a perfectly reasonable episode of Monkey, doesn't it? Themes of faith and redemption, par for the course? That "crucial detail" I mentioned before though...
The demon is a "Fraction Demon." Her son was being bullied by other demons for being no good at fractions, so she kidnapped the children who were good at fractions for him to eat their entrails and thus become (somehow) better at fractions.
The villagers fought against this by teaching all their children fractions wrong on purpose, and their houses were all covered with incorrect calculations, baffling Tripitaka and enraging Sandy as to why this should be so.
It just seems such a totally random thing to hang a story on. Monkey continues to astonish me with its craziness.