Underland chronicles volume 3
Penguin Random House Audio Publishing Group
Eleven-year-old Gregor and his younger sister, Boots, return to the Underworld beneath New York City to find the cure for a terrible plague that threatens the life of their mother, as well as the lives of the people, bats, and rats who populate the underworld.
Underland chronicles volume 1
When eleven-year-old Gregor and his two-year-old sister are pulled into a strange underground world, they trigger an epic battle involving humans, bats, rats, cockroaches, and spiders while on a quest foretold by ancient prophecy.