When Gregor falls through the grate in the laundry room of his apartment building, he hurtles into the dark underland where spiders and rats coexist with humans. This world is on the brink of war. A prophecy foretells that Gregor has a role to play in the underland's future. Gregor wants no part of it, until he realizes it's the only way to solve the mystery of his father's disappearance.