It seems the Wicked Witch, in her disembodied state trapped in the crystal ball, isn't relying solely on Wilhelmina, because she sends another band of Winged Monkeys (Lyman and Frank are nowhere to be seen) to take over the Emerald Forest, where the Lion is now king. Dorothy, Scarecrow, Tin Man, and Toto get wind of this and go to warn Lion, but he's in bed having caught a bug—not a cold, like Dorothy thinks at first, but a real bug running around Lion's head and making him miserable. After trying a few home remedies with no success, they go to Ozma, who gives Dorothy, Scarecrow, and Tin Man shrinking potions. They're going into Lion's head to confront the bug. Yes, it's a Wizard of Oz/Fantastic Voyage mashup! Our three heroes manage to drive the bug out, the Lion feels better and goes off to stop the monkeys, and the bug ends up in the head of the monkey chief! All's well that ends well!
There's not a lot else to add. It is very cute, however, that Ozma is blowing bubbles shaped like cubes, stars, pyramids, and other various non-spherical shapes.