The kids enter the Fire Nation with the goal of covertly moving from island to island to the Royal Palace, where they will eventually confront and defeat the Firelord. Along the way, they discover the people of the Fire Nation are not at all that different in their needs and desires from the other peoples of the world.

As the kids continue to prepare for the coming eclipse, Aang and Zuko learn about their shared past, Toph gets into trouble in a small Fire Nation village, and Katara learns a Water bending technique that she wishes she could unlearn. The action culminates in the Day of Black Sun. The long-awaited invasion of the Fire Nation will change everything. Or will it?