** Note: This episode contains "Frozen 2" spoilers. "Frozen" became the top-grossing animated feature of all time after its 2013 release, so creating a sequel to the beloved film about two royal sisters' unbreakable bond wasn't something "Frozen 2" writer/director Jennifer Lee took on lightly. Lee talks with ABC News' Ginger Zee about the challenges of crafting a new adventure for Anna, Elsa, Olaf, Kristoff and Sven, and being a creative leader at Walt Disney Animation Studios. - A rare behind-the-scenes look at the making of Frozen 2. For the first time, the Oscar-winning filmmakers of Walt Disney Animation Studios are pulling back the curtain, revealing the creative process that brought the next chapter in the Frozen saga to life! And step "Into the Unknown" with songwriters Kristen Anderson-Lopez and Robert Lopez for a sneak peek at Frozen 2's all-new soundtrack. Hosted by Ginger Zee of ABC News. A production of ABC Audio in collaboration with Walt Disney Animation Studios. Loving this series? Tell us with a rating and a quick review: http://bit.ly/2CZNQ4a