After being cryogenically frozen in an iceberg, Aang and Appa are awoken a hundred years later by two siblings of the Southern Water Tribe, Katara and Sokka. Aang learns that the Fire Nation started a war a hundred years ago, just after his disappearance. The Fire Nation's opening move in its campaign for global conquest was to launch a genocidal attack on the Air Nomads which drove Aang's entire people to extinction, thus making him "The Last Airbender" left alive. He realizes that he must fulfill his destiny of becoming the Avatar and return balance to the world by defeating the Fire Nation. Aang sets out to master the three unlearned elements: Water, Earth, and Fire. With Katara and Sokka, Aang decides to head to the North Pole to find a Waterbending master. Aang travels to a Crescent Island in the Fire Nation after contacting Avatar Roku in the spirit world. Upon instruction from Roku, he travels to the Crecent Island to a Fire-Sage temple wherein he contacts Roku on the solstice. Roku tells Aang that he must master all four elements and end the war before this time. Aang is told that Sozin's Comet, which Fire Lord Sozin used as a power supply to start the war, will return in the coming summer, giving the Fire Nation enough power to ultimately accomplish victory. For most of their journey to the North Pole, the group is pursued by Zuko, a banished Fire Nation prince and son of Fire Lord Ozai who is obsessed with capturing Aang in attempt to restore his lost honor since being banished and burned by his father for speaking out of turn.