This book contains the third and fourth novels in the Russian Oz-inspired "Magic Land" series. In "The Seven Underground Kings," Ellie and her cousin Fred arrive by accident in the kingdom of the Underground Ore-Diggers at a time of crisis, and help put things right. In "The Fiery God of the Marrans," villainous Urfin Jus, using an ordinary cigarette lighter, passes himself off as a god to the primitive Marran people, who do not even have fire, and makes them into a powerful military force to use to conquer the Emerald City.

This book, the last of three, contains the two final Oz-inspired "Magic Land" stories of the six written by Russian author Alexander Volkov (1891-1977). In "The Yellow Fog," an extremely wicked giantess-witch named Arachna tries to take control of Magic Land, and when the inhabitants refuse to submit to her, she unleashes a dreadful yellow fog on them. "The Mystery of the Deserted Castle" tells of some extraterrestrials from the planet Rameria who come to Earth with the idea of conquering it, and everything possible goes wrong with their grandiose plans