An Airbender comes to grips with his new reality as war erupts. A century later, a pair of Water Tribe siblings make a discovery that changes everything.

Aang, Katara and Sokka arrive at a small Island, home to elite warriors named after Avatar Kyoshi. The Fire Nation gets wind of the Avatar's whereabouts.

News of a traitor puts the trio at odds in Omashu, where a mechanist and rebels with a charming leader muddle their plans to protect the Earth Kingdom.

When the group lands in the Spirit World for a rescue mission, they come face to face with dangerous threats, painful memories and a mysterious entity.

A desperate Aang visits Avatar Roku for help on his journey as the Fire Nation closes in on him. At their fortress, a masked intruder breaks Aang out.

As an attack on the Northern Water Tribe looms, Katara challenges a master Waterbender, Sokka meets a princess, and Aang takes Kuruk's words to heart.

Zhao leads the Fire Nation into the North with a bold plan to weaken the Water Tribe. When the battle takes a dark turn, Aang enters a powerful state.