Gregor the Overlander

In this fantasy novel, eleven-year-old Gregor and his two-year-old sister Boots fall through an air duct grate in their New York City apartment building into the Underland, a subterranean world inhabited by humans, giant sentient bats, rodents, and insects.

Gregor learns about a prophecy that suggests he is the 'Overlander warrior' destined to stop the rats from taking over the Underland.

He embarks on a dangerous quest to rescue his father, who disappeared two years earlier, and to recruit allies for a war against the rats.

Along the way, Gregor faces numerous challenges and battles, ultimately discovering the true nature of the prophecy and his role in the Underland's future.