Ozma is getting ready for an extended trip to the annual meeting of Ozian dignitaries,, and giving Dorothy all kinds of directions about what to do in case of emergencies. They are all particularly concerned about the magic vault and all of its traps and other hazards, but Ozma reels off the directions for getting around them so fast that nobody can understand her. (That high squeaky voice with a vaguely British accent doesn't help!) Once Ozma takes off, Frank and Lyman report back to Wilhelmina and the Wicked Witch. Sure enough, the Witch wants to break into the vault. But they need a distraction! Wilhelmina and the monkeys raise a ruckus in Merryland, scaring the clowns who live there, and Dorothy and the guys spot this in the Magic Picture. So they leave the Wizard in charge of the vault while Dorothy uses the Ruby Slippers to whisk the others to Merryland. The Witch, disguised as a messenger, enters with a message from Ozma, needing a potion. The Wizard isn't much help, getting caught in the traps himself, so when Dorothy and the gang return, they use all their skills and abilities to get past them all and break in. (Hmm, did nobody notice that that messenger has green skin, a pronounced chin, and a couple of big hairy warts?) The Witch is in, and gleefully starts gathering items up—only for Dorothy to reveal that she knew the witch was the messenger the whole time! She tries to trap the Witch in the vault, only for the Witch to turn the tables and kick Dorothy out. But Dorothy manages to reset some of the traps, so when the Witch tries to leave, she ends up trapped after all, just waiting for Ozma to come back and deal with her.
Well, it was all very silly, and that's not a bad thing. Wilhelmina may be wising up, as she seems to be pretty nonchalant about what her auntie is doing, perhaps knowing that Dorothy and her friends are going to win in the end. Oh, she helps out with the distraction in Merryland, but that's just a fun romp for her. Meanwhile, Merryland! Yes, the writers know more about Baum than just his Oz books, and are mining it here. Anyway, overall, a fun little romp of an episode, but not the most crucial episode, either.