Dorothy, Ozma, and the gang are enjoying a picnic by the Truth Pond, which causes you to speak the truth while you're in it (so, not quite as bad as it is in the books). The Lion eats most of the pie, leaving only one slice left for Dorothy and Ozma. Not a problem, Ozma has brought along the Copy Cat, a glass cat statue that will duplicate anything you ask it to. Ozma creates two more slices, but then the Lion creates a mountain of them! (Hmm, maybe for story purposes they should have had the Hungry Tiger along in this story.) Wilhelmina, spying on them, decides to steal the Copy Cat and, at her aunt's urging, create an army of flying monkeys. Frank and Lyman steal it, but on the way back spot a lone banana on a tree and copy it. They eat more bananas than they've ever had in their lives, and can barely fly. Getting back to the castle, Wilhelmina smells their banana breath and decides to duplicate someone cleverer and better looking than the monkeys—herself! Before too long, there's a Wilhel-army attacking the Emerald City. Dorothy uses the Ruby Slippers to get everyone out, and so all the Wilhelminas have nothing to look for. There's one problem: All the Wilhelminas all think they're the original, and want to be in charge! Eventually, however, they get their stuff together and go searching for Dorothy all through Oz. Meanwhile, in Munchkinland, the gang hatches a plan: Any fake Wilhelminas touching the Truth Pond will disappear. So they create a fake pair of Ruby Slippers as bait, and put them on a lily pad in the Truth Pond. Sure enough, most of the Wilhelminas get wet and go poof. But four are left, and discover that the slippers they're going after are fake, so Dorothy perches herself up on the top of the fountain in the Truth Pond to attract them. Just as they're about to get her, she clicks her way out, they crash, all fall into the Pond, and three disappear. The final, real Wilhelmina is sitting there, telling all kinds of unpleasant truths to herself, getting totally wet.
For a show that generally plays things for laughs, this may be the biggest romp of an episode yet, and that's saying something. The creators of this show clearly had fun with the rules of the Truth Pond and how multiple Wilhelminas would get along (not well, as it turns out). But there is one big dangling thread: What happened to the Copy Cat itself? Last we saw Wilhelmina still had it, so maybe she can still cause some mischief with it.