When a mysterious vehicle follows Aang's group they try to escape but it appears every time they try to rest. They confront it, but Azula emerges and attacks and they are forced to run again. The tension grows among them and Toph leaves the group and finds help from an unlikely source. Meanwhile, Aang tries to draw their pursuers away and finally faces off against Azula. Zuko also arrives determined to claim his prize.

When Aang and his friends meet a professor who knows of a library that contains information about the world, Sokka decides to go there to try and find some information to use against the Fire Nation. The library is guarded by the knowledge spirit, Wan Shi Tong, who doesn't welcome humans into his library, because he believes they only seek information for evil purposes. When Wan Shi Tong discovers Sokka wasn't being truthful with him, he begins to sink the library, bringing the kids down with it. Will everyone be able to escape the library in time? And who are the strange benders who are trying to kidnap Appa?