It has been 3 years since the revolution ended.
Korra, Tenzin, Jinora and her siblings are enjoying an era of peace.
Suddenly, a white, blonde man wearing all black has approached the air acolytes.
He asks: "is this where Raava lives?"
The air acolytes where surprised by the question, but they answered anyway: "yes, the avatar lives here."
And then he said in a cold voice: "good, I found most of what I am looking for." And then he proceeded to walk to the airbending training ground.
When he saw Korra he asked: "are you the one called the avatar?"
She replied: "yes I am the avatar, is there anything I can help you with?"
He made a small laugh and said: "you will help me in more ways than you think." And then he took a small purple orb out of his pocket that caused a great darkness for a short time.
After that a purple spot in Korra's chest started glowing, Korra knew that it was Vatuu, but before she was about to waterbend the mysterious man threw what seemed like a blast of energy on her, she wasn't able to move, she knew she was paralyzed.
The mysterious man started walking toward her while she was struggling to move, she was unable to break free.
Korra shouted for help and everyone on the island came, but before they could do anything the mysterious man blasted more energy blasts at them paralyzing them as well.
As soon as he touched the purple spot Vatuu immerged from Korra's body.
Vatuu said: "thank you mortal for freeing me, why not join forces with me so we can fill this world with-"
The mysterious man interrupted: "you have no power over me spirit of darkness, you are but a mean to an end and I need you for my plans."
And then he moved the shadows around him to make a giant ball, trapping Vatuu within.
He then turned to Jinora who was still paralyzed and said: "oh my, I came here for half of what I wanted and find three quarter, how lucky am I."
Both Korra and Tenzin who were there shouted: "leave her alone."
Korra tried to enter the avatar state, but even that was not strong enough to break her free.
The mysterious man then made the ball that traps Vatuu that it could fit inside his pocket, then he blasted from his hand a block of ice on Jinora to make sure that she won't be able to resist, finally he pointed at the shadow of a tree that suddenly formed what seemed like a portal.
He went through with Jinora and the portal was closed.