When Aang leaves to aid Fire Lord Zuko with spiritual affairs in the Fire Nation, Katara and Sokka return to the Southern Water Tribe by themselves, where they are shocked to discover that their village has become a bustling city, with Hakoda in charge. The changes seem to have largely been due to the efforts of Malina, a member of the Northern Water Tribe who is seemingly striving for greater unification of the Water Tribes, but has unknown intentions.

Ever since the conclusion of Avatar: The Last Airbender, its millions of fans have been hungry for more - and it''s finally here! Think of this as the Book Four (season 4) of Avatar because it continues Aang's story from right where the TV series left off. This series rejoins Aang and friends for exciting new adventures, beginning with a face-off against the Fire Nation that threatens to throw the world into another war, testing all of Aang's powers and ingenuity.

Avatar Aang asks his friends to help him honor Yangchen's Festival - an extremely sacred Air Nomad holiday that has not been held in over a hundred years.
However, cryptic visits from the spirit of Avatar Yangchen herself lead Aang to discover a jointly owned Fire Nation and Earth Kingdom refinery - operating on land sacred to the Airbenders! Is this the cause of the pollution Aang finds there, or is something more mysterious happening?

Preview from Dark Horse

For years, fans of the animated series (Avatar: The Last Airbender and The Legend of Korra) have been burned with one question - Wwhat happened to Zuko's mother? Finding a clue at last, Fire Lord Zuko enlists the aid of Team Avatar - and the most unlikely ally of all - to help uncover the biggest secret of his life.
An Earth Kingdom Scholar's points of view about "family" and governing with dignity motivates Zuko to set things right within his own family. He makes a deal with Azula, releasing her from the mental institution in exchange for her help on his quest to discover the truth about their mother, Ursa. Additionally, with the help of Aang, Sokka, and Katara, the five set out on a journey towards Ursa's hometown. Tensions between Azula and the rest stir trouble and an encounter with a wolf spirit delays them even more, though as they continue, they find their own dynamic to make it all work.