The story explores the origins of the Avatar, showing Wan (Steven Yeun) as he becomes the first Avatar by bonding with the light spirit, Raava (April Stewart), to beat Vaatu at Harmonic Convergence.

Wan fought to maintain the peace, but in the end, he died in a divided world, and Raava's spirit moved on to create the second Avatar, one of many future Avatars to succeed the historic Wan.