Shortly after moving into a new house, 12 year-old Russell discovers something weird under his bed - a trap door leading to the fantastic world of Under! Russell is crowned King of Under, and boy, does his kingdom need help! For years, Under was ruled by the evil King Cliff the Grim (who used to live in Russell's room), and now it's up to Russell to put things right. It's also a time to make new friends, to explore and to find adventure. Yes, Russell is the King, but he's also a boy with a talking dog in a strange and wonderful place. The series follows the astonishing adventures of these characters and how King Russell struggles to remain King under trying circumstances.