The Legend Of Korra Episode 3.03 The Earth Queen

Team Avatar arrives in Ba Sing Se. While Korra has an audience with the Earth Queen, the others notice that Kai has gone missing, prompting Mako and Bolin to go look for him. They track him down, but he manages to shake them in the monorail, which takes the brothers to the Lower Ring, where they eventually run into their family from their father's side. Meanwhile, Korra and Asami set course for a small village to collect taxes as a favor to the Queen. After getting her money, the Queen brushes off Korra's request for help in tracking down the airbenders, leaving the Avatar to storm out of the palace. In the city, Kai found himself arrested by the Dai Li and subsequently conscripted in the Earth Queen's first airbending regiment.