Okay, this is going to be cliffnotes, but it may still take a while. The 'last episode' is actually two episode called 'The Last One' part 1 and part 2: Erica is taken to hospital where she gives...
in the last episode i think goku sees his grandfather he ends up saving chi chis father who is trapped in a fire and goku and chi chi end up getting married. (i think)
Zuko becomes firelord, Azula gets locked in a mental hospital, ozai is in prison, aang and katara make out, and zuko and aang promise to reconstruct the world Then Katara finds out that she likes...