A young dog named Rover is happily playing with his yellow rubber ball when he meets a cross old man. Rover sends the man on his way, tearing his trousers in the process. Sadly for Rover, the old man is Artaxerxes, a powerful wizard from Persia. Artaxerxes turns Rover into a toy dog, and sends him off. This is the start of an epic quest for Rover, who meets a sand-wizard, the Man-in-the-Moon, the great dragons that live on the moon, the many merfolk living at the bottom of the ocean, and a delightful little boy.