S2E10 · Book Two: Earth - Chapter Ten: The Library

Complete story — includes the ending

Sokka decides the group needs some intelligence to defeat the Fire Nation. At an oasis, the group encounters Professor Zei from Ba Sing Se University, who tells them of Wan Shi Tong's library in the Si Wong desert, said to contain a vast collection of knowledge. The professor and the group eventually locate the library nearly buried, but intact inside. Toph refuses to descend with the others and stays outside with Appa. Wan Shi Tong, a large spirit owl, tells the group that humans are no longer permitted in the library, as they only seek knowledge to gain an advantage over other humans. The group convinces him otherwise, and begin searching for information. Sokka discovers a crucial weakness of the Fire Nation that could end the war: an upcoming solar eclipse will prevent firebending for its duration. Wan Shi Tong catches them in their lie and refuses to allow them to leave with the knowledge. He begins sinking the library before chasing the group. Outside, while Toph is busy keeping the library afloat, Appa is kidnapped by a gang of sandbenders. As Professor Zei stays behind, too fascinated by the knowledge in the sinking library, the others escape but Aang is devastated by the loss of Appa. Note: This is part one of the 44-minute special "The Fury of Aang".