Avatar: The Last Airbender Season 1 Episode 7 : Winter Solstice: The Spirit World (1)
Aang finds himself in a small Earth Kingdom village that is being attacked by a monster from the Spirit World. One night, this monster (named Hei Bai) captures Sokka. Aang decides to go after him. But after Aang is knocked out, he accidentally ends up in the Spirit World. There, he is told that Avatar Roku has a message for him. Aang proceeds to calm the attacking beast, restoring peace to the village. Meanwhile, Iroh gets captured by the Earth Kingdom. The soldiers who captured him wish to take him back to Ba Sing Se to face justice, the city Iroh laid siege to for 600 days during his youth as a Fire Nation general. This causes Zuko to stop his chase for the Avatar and to instead go after Iroh.