The Legend of Korra - Book 3 (Change)
Episode 2: "Rebirth"

Description: Tenzin, Jinora, and Team Avatar try their best to recruit new airbenders, but keep getting rejected until a delinquent Earth Kingdom boy named Kai agrees to come along to Ba Sing Se. Elsewhere, an elderly Zuko appears to intercept the released prisoners and tells his guards that the Avatar must be protected from the new impending threat.