Roverandom, like many of Tolkien's stories, was originally told to Tolkien's two sons. When young Michael Tolkien lost his favorite toy, a little lead dog, J.R.R. Tolkien created the story of Rover, a real dog transformed into a toy, to console him.

Rover, a very small and very young dog, has the misfortune to annoy a wizard and is turned into a toy as a result. While searching for a way to regain his true form, Rover is sent on many adventures; to the moon, where he plays with the Man-in-the-Moon's dog (also called Rover), visits the dark side of the moon and annoys a dragon; to the depths of the sea, where he plays with a mer-dog (called Rover). Artaxerxes, the magician who transformed Rover, is an important personage under the sea, and Rover (now called Roverandom) eventually gets the chance to ask for his own form again, but several events intervene and it is some time before he is able to return to his own life.

The sand-sorcerer in Roverandom was inspired by the psammead in Edith Nesbit's Five Children and It