In episode five of the live-action “Avatar: The Last Airbender,” Aang and his friends are forced to enter the spirit world in order to find out why an angry spirit is attacking a small town. While there, they meet a giant owl spirit — Wa Shi Tong, who shows up in season 2 of the animated series and again in “The Legend of Korra.”
In the animated series, the spirit world was a big deal, essential to the story, and also part of what made the “Avatar” universe unique, seeing as its fantastical elements were grounded in spirituality. In Netflix’s “Avatar: The Last Airbender,” the spirit world is shown earlier than fans may be expecting and we see more of it, including a subplot where Sokka and Katara get kidnapped by Koh the Face Stealer and taken to a spirit prison. That prison is not from the original cartoon but instead from the sequel show, “The Legend of Korra.”
The Fog of Lost Souls is a prison for humans within the spirit world, presided over by a fog spirit that slowly pushes humans towards having a mental breakdown by holding them in their memories. This happens in the live-action remake, where Katara and Sokka are forced to relieve their most painful memories. It is in this very prison that Zhao spends eternity in the sequel series after his defeat. Connecting Koh to the spirit prison is a cool way of linking both “Avatar” series and expanding the world without completely making new things up.