A young girl named Alma finds a mysterious stone, which allows its owner to freely travel through the dimensions of time and space. An evil scientist named Mommy learns the stone's powers and wants to use the stone to conquer the world. Along with his dull-witted but muscular henchman, Marrow, he attacks Alma in an attempt to steal the stone from her. While they are scuffling, the stone’s magical power suddenly starts to work, and all three of them are transported to a rural town, where a brave young adventurer named Roy lives. Roy rescues Alma from the wicked pair, but the villains manage to escape with the stone. The two children board a magical railroad truck and chase after the villains in order to get Alma's stone back and save the world.