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.

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.

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.

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.

In captivity, Aang meets a king with a taste for games. To find their friend, the siblings must navigate a dark tunnel — and put their differences aside.

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.

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.

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.