Gregor the Overlander, by Suzanne Collins, is the first book in The Underland Chronicles. This book starts off as most would imagine a stereotypical adventure story beginning: By the main character falling into a hole in his house, which is actually a long dark bottomless pit! Well, actually, it's not bottomless, but it seems like it though. At the bottom, Gregor finds his sister, who also fell into the hole. They try to escape and return to the Overland, but encounter giant insects, rodents, and other creatures as well. They even find humans in the Underland, but these humans are different than you would expect. As Gregor leads his sister on a journey to reach the Overworld, they encounter some friends and foes as well as some drama among the groups of people (well, I guess you'd call giant talking insects "people") living in the Underland that they help to resolve.
This book's storyline is actually a lot deeper (pun intended) than most other adventure books I've read. Before they fell into the Underland, Gregor and his sister had also lost their father recently, and they begin to wonder if his fate was the same as theirs as they struggle to deal with their loss. I love the heart that Gregor has for his sister. I also love his willingness to be the leader the people need him to be, even though he doesn't want to. He steps up to do what he knows to be right. Great book!