Gregor the Overlander by Suzanne Collins
Gregor is stuck watching his two year old sister, Boots and his grandma for the summer. During the laundry session, his sister looses her ball in the grate and they both get sucked into the Underland. The Underland is filled with giant bugs, spiders, and rats. He just wants to get back home, but discovers two things. The first is that a prophecy foretells a role for him in the future of the humans living in the Underland. And second, the mystery of his father's disappearance is uncovered. The quest all unfolds as the mysterious prophecy plays out.
This book started a bit slow for me. I really didn't get into it until about the fourth chapter or so. It did pick up though, and I did enjoy it overall. I really appreciated the research on the different animals used to create their characters and attitudes. I was inclined to go and read about rats and their teeth, to find out if the fact was true or not. I think it is a great book for boys because of the quest and adventure. They would love that part for sure.