Set two weeks after the end of Book Two: Spirits, the world is dealing with the changes caused by the energy shift of the planet due to Harmonic Convergence and Korra's battle with the Dark Avatar. Among those changes is the reemergence of airbenders. The journey begins to rebuild the air nation, however, not all airbenders are friendly. Korra faces a new threat, a secret organization of terrorists who seek to bring down the world's governments and, once and for all, put an end to the avatar cycle.