The story begins on a specific day in Oz history — the day that Ojo and the Shaggy Man and their companions arrive at the Emerald City, when Dorothy meets the Patchwork Girl, the Woozy, and the Glass Cat for the first time. (See The Patchwork Girl of Oz, Chapters 13 and 16.) On this first meeting, Gannaway has Bungle confront Toto privately about the dog's inability or unwillingness to speak.
It turns out that Toto is laboring under an evil enchantment, placed upon him by the Wicked Witch of the West during his and Dorothy's first adventure in Oz. Whenever Toto tries to speak, spectral mastiffs confront and inhibit him. Within his speechlessness, Toto is actually a tortured soul. The Glass Cat's intellectual vanity overcomes her emotional coolness and self-absorption; she suggests that Toto can solve his problem by immersing himself in the Truth Pond. Toto makes the attempt — though he needs an extra boost of confidence from Bungle before he can overcome his ghostly canine oppressors.
The stratagem works. In the end, the black dog and the glass cat are something almost like friends.