Although as silly in its own way as The Minx and The Slug, with a large section of the episode set inside a monster's stomach, I enjoyed this one a lot more because the underlying plot held dramatic tension that the last episode lacked.
Two monsters - a Catfish-spirit and a faceless shape-changer (somewhat resembling the faceless enemy from Sapphire and Steel when not disguised as Pigsy), are locked in a conflict in which neither has the upper hand, but whenever they fight terrible earthquakes devastate the surrounding country, leading a living saint, San Cho, to try and mediate between them.
After a brief encounter with the shape-changer to begin with, the pilgrims meet San Cho and he informs them that the shape-changer is among them, disguised as one of the four. Unable to trust each other they go their separate ways until first Sandy and then Monkey are eaten by the giant Catfish.
There are then a number of really surreal scenes set in the monster's belly, in which Monkey and Sandy meet the Spirit of the Blue Pool - a fairy maiden that the Catfish had previously swallowed - and then the three of them, affected by the wine the Catfish drank, dance to a gramophone recording of the Monkey theme tune.
After this they discover that Pigsy is also down there with them, and has been down long enough that they deduce that the Pigsy they left behind was really the shape-changer.
Outside the Catfish's body, San Cho is trying to mediate between the two monsters as to which one should get to eat Tripitaka. A game of Go is the fair way, but the loser takes this poorly and a fight begins. Luckily Monkey manages to force the Catfish to cough him (and Pigsy and Sandy) up at this point, so they join the fight and win the day.
The powers of the Catfish and the shape-changer are used really well here, and the whole story fits together nicely. The humour complements the drama (the inside-the-monster sets would be impossible to take wholly seriously anyway) and so I'm glad I've finally seen this particular story.
I wonder if it will turn out there are others I have previously missed? If so I hope they are as good as this one.