The story opens with a bang and a splash: an underground spring erupts in a geyser that blasts Mandy into the sky.

The force propels her across the Deadly Desert to Oz; she lands in the little principality of Keretaria in the Munchkin Country, her impact cushioned by the power of a magic blue daisy.

Mandy finds a silver hammer, and meets a white ox with golden horns; she blunders into the court of King Kerr of Keretaria and his courtiers.

Nox is preoccupied by the political situation of Keretaria: the rightful king, a boy named Kerry, has disappeared, and his throne has been usurped by his uncle Kerr.

When a clue indicates that King Kerry can be found at a place called the Silver Mountain, the enterprising Mandy leads Nox on a search for the missing monarch.

Wutz controls a subversive network of spies and secret agents located in many parts of the land of Oz.

With the hammer and elf, the blue daisy, and Nox's magical horns, Mandy and the ox escape confinement, find and rescue King Kerry, and reach Ozma's palace in time to frustrate the plans of Wutz and Ruggedo.

In the poem, Mandy is an artificial and created being, made of "wood and tin...wire and cloth and plaster...." She was built as a sort of domestic robot to perform housework.

The principal villain, the Wizard Wutz, is another unusual character for Oz: a handsome, smooth, graceful but pure-evil villain who commands a hierarchical organization of subversives, with planted spies in positions of power all over the land of Oz, and a systematic collective strategy for overthrowing the government.

"[5] In the 1983 Dictionary of Literary Biography, Michael Patrick Hearn was less than impressed, writing, "In her last Oz books, Thompson wildly stretched her imaginative powers, at times risking loss of the child's perspective...