"The Legend of Korra: Balance" will be the final story of Korra. Nickelodeon has released the trailer for Season 4 and it offers a great preview of what's in store in Book 4.

The wait wasn't that long, but no one's complaining. Nevertheless, Korra returns in "The Legend of Korra: Balance" three years after Book 3. It can be safe to say that a lot has changed since.

In Season 4, Korra sets out on an adventure to restore balance in the world. She will face a very bad villain, but the villain is still a secret.

In the Book 4 trailer, it is seen that Korra has short hair and the kids have grown up, which just makes the story very realistic. Everyone is older and of course, over the years, a new villain wants to destroy the world once again. Also in the trailer, a guy with twin blades is shown. Tech Times wonders if this guy is Sokka's son.

Going back to Korra, she doesn't look happy at all. She looks so torn apart and depressed, which makes fans wonder what happened to her in those three years.

Then nearing the end of the trailer, Korra finds Toph. However, it isn't shown if Toph is okay or not. Through looking at Korra's reaction, Toph seems to be in a bad condition. But this begs the question, how can Toph have survived this long? Could something supernatural have happened?

What happened to Korra and Toph will surely be answered in the TV series. But if there's one sure thing right now, it's that Toph is alive and they will be rescuing the world once again. "The Legend of Korra" will definitely want to end the series with a bang.

"The Legend of Korra: Balance" premieres on Nick.com and Nick mobile app on Oct. 3.