Mako

Zhao’s invasion breaks through the outer wall of the Northern Water Tribe’s defenses, and he reveals a sinister plan. Aang goes to the spirit world for help – but will he return in time to stop Zhao and prevent the destruction of the Water Tribe?

Congressman Santos (recurring guest star JIMMY SMITS) masterminds a plot to pass the President's stem cell bill while the Republicans aren't paying attention. Members of a group of middle school children who are part of the Future Leaders for Democracy visit the White House and seek out Toby to discuss the voting age. And Kate deals with an impending invasion of Canada. Series star RICHARD SCHIFF directed the episode. Also available on iTunes and VUDU

Episode XLVIII (Jack vs. Aku) Tired of all the bounty hunters and robots failing, Aku fights Jack, mano y mano.

Niles is discouraged that his ideas for a psychiatric book have already been done. Determined to please potential publisher Sam Tanaka, Niles introduces him to his 'celebrity brother' Frasier. Sam mistakenly assumes that Niles's latest book proposal is a joint effort with his famous sibling, and thinks the concept is a winner. Reluctantly, Frasier agrees to join Niles in the venture. With visions of fame and fortune dancing in their heads, the Cranes are nonetheless unable to compose a single sentence together. Frasier invites Niles to the radio station, where they hope to turn callers' problems into fodder for their book. After their publisher requests a copy of what they've written so far, Niles and Frasier take the drastic step of sequestering themselves in a hotel room. As the hours pass, the isolation exacerbates their deep-seated sibling rivalry and they end up having a knockdown fight. At last, they realize that their dreams of literary stardom are not meant to be.