In Book Two, the Spirit and Human worlds are colliding and Team Avatar must embark on a journey diving deep into the mythology of the mystical Spirit World, encountering creatures like nothing they've seen before, and discovering the truth about the very first Avatar!

Book Four is set three years after Book Three. Now broken and bruised, Korra begins a journey of self-discovery and survival as the strong prey upon the weak. When an aggressive military force rises up led by the power-hungry Kuvira, the fate of the Earth Kingdom hangs in the balance and only the Avatar can set things right.

Set two weeks after the end of Book Two, Book Three finds Korra discovering that new Airbenders are popping up all over the Earth Kingdom. While she tries to find these Airbenders and rebuild the Air Nation, a group of dangerous criminals embark on a mission of their own.

Avatar Aang, the world's last Airbender, learns of an ancient power that could save his culture from extinction. With the help of his friends, he embarks on a global quest to find it before it falls into the wrong hands and threatens to upend the peace they sacrificed everything to achieve.