Kim accidentally becomes bonded with The Amulet of the Monkey King and begins transforming into a monkey, but is kidnapped by Monkey Fist who intends to get the amulet back. Meanwhile, Ron finds a monkey he believes to be Kim and looks desperately for a way to change her back, while avoiding the complications Josh Mankey's attention may provide.
There are actual Chinese tales about the Monkey King, but in the actual Chinese tales there is already a Monkey King named Sun Wukong. The most well known story about Sun Wukong is the ancient Classic Chinese novel Journey to the West so it is possible the writers of the story made an error or altered the story for the episode.
This is the second time a villain goes after Kim thanks to a piece of jewelery, but this time she is actually kidnapped.
This is the second time that Ron overcomes his fear of monkeys long enough to befriend one.
This is the only time that any of the Monkey Ninjas is revealed to have a name or established gender: Chippy, who is female.