The Siege of the North Part 2.Zuko struggles to find shelter, while Sokka, Katara and Yue search for him and Aang. Fire Nation forces assault the Water Tribe city. When Aang returns from the Spirit World, Sokka, Katara, and Yue are able to follow his spirit to his body. Admiral Zhao slays the moon spirit, Tui, in spite of warnings from both Aang and Iroh, who explain that the whole world depends on the moon. Without the moon the waterbenders lose their ability to waterbend. Aang goes into the Avatar State and, joining with the Ocean Spirit La, decimates the Fire Nation armada. Zuko fights Zhao, while Iroh remains with Team Avatar to try to revive Tui. Iroh recognizes that Yue was touched by the moon spirit as a baby, and Yue gives back that spark of life, sacrificing herself to save the Moon Spirit after sharing a final kiss with Sokka. Zhao is pulled underwater by the Ocean Spirit in retaliation for slaying the Moon Spirit, refusing to accept Zuko's help when he attempts to save him. At the end of the episode, Firelord Ozai, Zuko's father, assigns Zuko's sister, Azula, to hunt down her traitorous uncle and brother.