Avatar: The Last Airbender - The Rift, Part 2 (The Rift, #2)

The Past Returns!

Avatar Aang and his friends seek answers to the mysteries surrounding a refinery on land sacred to the Air Nomads. As Toph discovers a startling truth about her father's involvement with the refinery, Aang travels to the spirit world, discovering a secret as surprising as it is dangerous. Soon, Team Avatar realizes that they may be facing a threat more dire than they could possibly have imagined!