In commemoration of Avatar: The Last Airbender's 15th Anniversary, Dark Horse Comics is releasing The Legend of Korra: Ruins of the Empire Library Edition for the fall.

The Legend of Korra: Ruins of the Empire Library Edition combines the three-volume series into an oversized hardcover, and will come with a sketchbook section with artist commentary. The 240-paged book is priced at $39.99. Preorders are now available at your local comic shop, Barnes & Noble, and Amazon.

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"On the eve of its first elections, the Earth Kingdom’s future is endangered by its past. As former Earth Empire leader Kuvira works to reclaim her honor, the devious commander Guan undermines the peace Avatar Korra has established to take power for himself. Korra and Kuvira must learn to work together to ensure the future of the Earth Kingdom," the book's official description reads.

The hardcover is written by the show's co-creator Michael Dante DiMartino with art by Michelle Wong. Avatar and The Legend of Korra co-creator Bryan Konietzko and animated series writer Tim Hedrick provide consultation on the project.

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The Avatar sequel series aired from 2012 to 2014 with a total of 52 episodes over 4 seasons. Created by Michael Dante DiMartino and Bryan Konietzko, The Legend of Korra stars Janet Varney as Korra, David Faustino as Mako, P.J. Byrne as Bolin, J.K. Simmons as Tenzin, and Seychelle Gabriel as Asami Sato. The series, along with Avatar: The Last Airbender, is now available on digital and Blu-ray.

The Legend of Korra: Ruins of the Empire Library Edition 240-paged book is priced at $39.99. Preorders are now available at your local comic shop, Barnes & Noble and Amazon. It arrives in comic shops Sept. 9 and in bookstores Sept. 22.