It was supposed to just be a normal basement--some storage boxes, dust, you know, the usual basement stuff. But when Milo is sent by his mother to fetch a sock from the basement of the historic home they've moved into, Milo finds a door in the back that he's never seen before. Turns out that the basement of his house is enormous. In fact, there is a whole world down there. As Milo travels ever deeper into the Basement World, he meets the many Things that live in the shadows and gloom...and he learns that to face his fears he must approach even the strangest creatures with kindness.