Ozma and the Munchkins throw an old fashioned Kansas-style country fair for Dorothy. Wilhelmina gets jealous, and uses a magic locket to turn into Dorothy's double. The wearer looks like whatever is in the picture in the locket, so Lyman draws a picture of Dorothy (after a few false starts). Dorothy keeps winning prizes and passes them along to the Munchkins, but Wilhelmina then comes along and grabs them, causing the Munchkins to resent Dorothy. They demand Ozma revoke Dorothy's princesshood (or is it princesship?), but then Wilhelmina turns up, causing the two Dorothys to convince the others which one is real. Eventually, Dorothy removes the locket, exposing Wilhelmina, who takes off in a huff. All is forgiven, and Dorothy is still a princess.
This was just a fun, silly one, with all kinds of fun little character moments. Nobody new turned up from the books, but the ballonapig sure could have. Wilhelmina just wants some of the goodies, but her auntie keeps bugging her to get the Ruby Slippers. The Wicked Witch of the West also isn't quite sure how looking like Dorothy will help Wilhelmina get the Ruby Slippers, and keeps leaving messages on Wilhelmina's compact. At one point Dorothy and her friends play Keep Away with the locket, causing Toto, the Scarecrow, the Tin Woodman, and the Cowardly Lion to all look like Dorothy (mostly). And after leaving, Wilhelmina keeps popping back in to take more goodies, continuously interrupting the Munchkins' attempts to apologize to Dorothy.
At this stage, I think I can say that I am really enjoying this series. It's generally played for laughs, and definitely should not be taken as a serious attempt to adapt Oz, but if one approaches it with the right expectations, I think most people will enjoy it.