"The Underland Chronicles" is a five-part series of fantasy novels written by Suzanne Collins between 2003 and 2007. It tells the story of a boy named Gregor and his  adventures in a land, called the "Underland", hidden under New York  City. The Underland is inhabited by humans, who live in the stone city  of Regalia, along with various giant versions of such creatures as bats,  cockroaches, rats, and spiders. According to the author, the series  involves many topics relating to war, including biological warfare,  genocide, and military intelligence