Avatar: The Last Airbender: The Search Part 3

Avatar Aang travels to the spirit world to parley with an ancient power, bringing Fire Lord Zuko ever closer to discovering the truth about his mother's fate-and his own past.
Yet Zuko's sister Azula is becoming increasingly dangerous, threatening to ruin everything that Zuko, Aang, Katara, and Sokka have struggled to achieve on their search!