Synopsis:

  Remember Speedy, the little boy who once arrived in Oz by a space rocket from Long Island, New York USA in The Yellow Knight of Oz?

  Well, this time his beloved Uncle Billy again misses out on the adventure. Together, Uncle Billy and Speedy go camping in Yellowstone National Park. While examining the skeleton of a dinosaur, one of the park's famous geysers blows – sending Speedy and the skeleton remains sky high. The dino skeleton magically becomes alive and thus is born Terrybubble - an honest-to-goodness live dinosaur, with all of the lovable characteristics of a faithful dog, without that all that annoying flesh and skin. Because even alive, Terrybubble is still a skeleton!

  Elsewhere, King Sizzeroo of Umbrella Island (an island so named because everyone has an umbrella attached to them – cows and cats, too!) is bored and wishes to travel – but without leaving his island. Waddy the court magician cleverly solves the problem by building a huge magic umbrella over the island. Immediately, it became a floating island in the sky.

  One day, while floating over the red Quadling Country of Oz, Umbrella Island accidentally hits Loxo the Lucky on the nose. Loxo - a tremendous wandering giant - seizes the handle of Umbrella Island and holds it captive, demanding King Sizzeroo's daughter, Princess Gureeda, as a slave to tie his boots. The Princess is so named because she reads so much and so greedily, but she will soon find her own life as exciting as any she has read about!

  Meanwhile, as the velocity of the geyser blow begins to slow, Speedy worries about the old adage that "what goes up, must come down" – that is until Terrybubble suggests they grab hold of the purple mountains that they are rapidly approaching above them. Next thing they know, they are on solid ground... still in the sky... on Umbrella Island.

  Although young Speedy does a valiant job protecting Princess Gureeda, outwitting Kachewka - Umbrella Island's crafty and unscrupulous Royal Counselor - and fighting the forces of the Sea King, aid eventually comes from old friends Ozma, Dorothy, the Wizard of Oz, Scarecrow and Tin Woodman.

  Note: When asked in a 1963 interview to name her favorite Oz tale of the 19 she had written, Ms. Thompson named Speedy in Oz as the one she was most proud of.