What would you do if you discovered a whole new world beneath your own feet, in the depths of your own sandbox? Would you explore the world, and learn its magical secrets? Or would you run away from the countless evil beasts that swarm the underground? Unfortunately, for young siblings Tommy, David and Rin, they do not have a choice in the matter. Once they fall into a portal down their own sandbox, they realize they are trapped in the underground world. With no clear way out, they must work together to survive and find their way back home. It doesn't take them long to realize they can control a form of magic called "the Gleam", which they use to free their new, quirky goblin friend, Deek, from imprisonment. Join the three siblings, along with Deek, on their adventures: solving puzzles, battling monsters, and trying to decide whether to help save this new world, or simply find the quickest way back home.