The world was once kept in balance by four nations: the Water Tribe, the Earth Kingdom, the Fire Nation, and the Air Nomads.
The sole being entrusted with maintaining that balance was the Avatar—the one who could wield all four elements: water, earth, fire, and air.
But when the Avatar suddenly vanished, the Fire Nation began a war, plunging the world into chaos.
One hundred years later, a girl of the Water Tribe named Katara and her brother Sokka awaken a boy who had been sleeping within an iceberg.
He is none other than the legendary Avatar himself—Aang.