The Wizard's working on his magic some more, but it's not going quite as well as anyone wants it to. In fact, a whole lot of things are disappearing from the Emerald City and appearing in the land of lost magic items under the rainbow. So much stuff is disrupting the place that the Undertaker comes up to Oz to investigate and punish whoever is causing such a mess. Once he finds the Wizard, he takes him and everyone with him—of course that would mean Dorothy, Toto, the Scarecrow, the Tin Woodman, and the Cowardly Lion—and confines them there. Of course the Undertaker is no fool; to keep them from escaping, he confiscates the Ruby Slippers and locks them in a magical cage. So, Dorothy reasons, it will take magic to get them out. But the only one of them who knows magic is the Wizard, whose magic got them into this mess in the first place. Lots of failed trials convince the Wizard that he isn't worthy of their faith, and he decides he's done with magic. But Dorothy helps the boys see that all he needs is a little confidence, and she hatches a cunning plan. Remembering the Scarecrow's diploma, the Tin Woodman's clock, and the Lion's medal, they give him a symbol of what he already has inside of him: A wizard's hat. (Yes! He finally takes off Professor Marvel's turban!) Sure enough, it gives him the focus and confidence to unlock the cage and, just as the Undertaker has come again, clean up everything that he messed up in the first place. They get back to Oz safe and sound, and the Wizard is a better wizard for it.
Not bad, another harmless little episode. We get a nice little tour of Oz as the Undertaker looks for the troublemaker, seeing Ozma, Glinda, and the Wicked Witch and Wilhelmina doing some magic. The callback to the Wizard giving gifts to Dorothy's friends and them turning the same table on him was a nice little touch. Let's hope the Wizard is a more capable magic-user from now on.