Finally arriving at their destination of the Northern Water Tribe, Aang must master Waterbending, and together with his friends, defend the city from Admiral Zhao's greatest attack yet! Chapter 17: The Northern Air Temple After hearing rumors about surviving Airbenders, the kids journey to the Northern Air temple to see for themselves. Chapter 18: The Waterbending Master The kids reach the Northern Water tribe, and Aang and Katara look for a Waterbending Master. Meanwhile, Zhao plans an attack and Zuko continues his quest for the Avatar. Chapter 19: The Siege Of the North, Part 1 The Northern Water Tribe braces itself for an attack by Admiral Zhao's Fire Navy fleet. In the heat of battle, Aang struggles to defend the city. Chapter 20: The Siege Of the North, Part 2 Zhao's invasion breaks through the outer wall of the Northern Water Tribe's defenses, and he reveals a sinister plan to destroy the city.