The Legend of Korra - Book 3 (Change)
Episode 8: "The Terror Within"

DescriptionIn Zaofu, Korra and Bolin continue to learn metalbending, and Opal leaves for the Northern Air Temple. At night, Zaheer and his team infiltrate Zaofu and capture Korra. But Lin and Suyin rescue her, and the assailants retreat. In the subsequent investigation, Korra and her friends discover that Suyin's advisor Ai Wei had been aiding Zaheer, but he too escapes through a secret tunnel. Later, Korra, Asami, Mako and Bolin sneak out of Zaofu to pursue Zaheer and his allies.