Epic adventures have small beginnings, like the family dog discovering a hole in the backyard. It's big enough for four siblings to enter... and the mysterious tunnels that it leads to are larger still. Maybe exploring those tunnels wasn't wise. But how could they resist? Who would have known what perilous journeys and magical worlds awaited them? Now each must draw on all their courage, strength, and wit to find a way back to each other— to find a way home. Welcome to The Undergrounds! Enter at your own risk...