Prepare yourselves, "Legend of Korra" fans. The physical world and the spirit world will soon collide on the Emmy-nominated Nickelodeon series -- posing the biggest threat yet for Korra -- when Book 2 premieres on Sept. 13. And we have an exclusive sneak peek at the action for you now!

Sure, Republic City is free of Amon and the Equalists thanks to Korra, but now it's been six months, and "she and her friends will face impossible new dangers," the promo reveals.

[Related: 2013 Nickelodeon Kids' Choice Awards: 5 Best Show Moments]

Korra -- the only one who can bend water, earth, fire, and now air -- is not sure she can handle all the responsibility. "Maybe I'm not ready to be the Avatar," she confesses. But her journey has just begun, and with benders under attack and the spirit world out of whack, it's her job to fix things.

And for the first time ever, the headstrong protagonist will venture into the parallel plane of the spirit world, where all the immortal, supernatural, and spiritual entities exist.

"The Legend of Korra" Book 2 premieres Friday, 9/13 at 7 PM on Nickelodeon.





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