ook Two: Spirits (神靈) is the title of the second book of The Legend of Korra, created by Michael Dante DiMartino and Bryan Konietzko. The nomenclature refers to the focus of the season, a conflict involving the Spirit World.
The book debuted on television on September 13, 2013, though the first episode, "Rebel Spirit", was originally shown to San Diego Comic-Con attendees on July 19, 2013. Spanning fourteen episodes, Book Two concluded on November 22 of the same year. The book also features a two-part special titled "Beginnings", which explores the background of the first Avatar, Wan. It is followed by Book Three: Change.Overview from themoviedb.org