Avatar: The Last Airbender: The Rift, Part 3 (The Rift, #3)

The spirits are restless!

As Avatar Aang and his friends confront an ancient spirit determined to destroy a town on land sacred to Air Nomads, Toph and Aang find themselves on opposing sides in a battle of gigantic proportions. If Toph and Aang don't put aside their differences, there's more at stake than just their friendship!