When Gregor falls through a grate in the laundry room of his apartment building, he hurtles into the dark Underland, where spiders, rats and cockroaches co-exist uneasily with humans. This world is on the brink of war, and Gregor's arrival is no accident. A prophecy foretells that Gregor has a role to play in the Underland's uncertain future. But Gregor wants no part of it-until he realises it's the only way to solve the mystery of his father's disappearance. Reluctantly, Gregor embarks on a dangerous adventure that will change both him and the Underland forever.