"The gang is back together. And literally it's like we never went away," says Gad. "Every day we're reminded of Frozen in our lives. So it feels like a continuation of a saga that has many parts still untold. It felt like coming home again after a short absence."
The first revisiting of the now-beloved characters features some surprising changes, including older sister Elsa's attitude. Elsa, weighed down by her royal duties in Frozen, has lightened up so much that she's throwing Anna a birthday bash.
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"It's another side of Elsa the audience hasn't seen before and we hadn't really played with in the original feature," says Chris Buck, who reunited with Jennifer Lee to direct the short.
The birthday plans go awry when the powerfully magic Elsa comes down with a cold on the big day.
"Elsa doesn't get a cold in the usual way," says Lee. "She's special. Surprising things occur that wreak a little havoc."
The short features a new song from the husband-and-wife team of Robert Lopez and Kristen Anderson-Lopez, who won an Oscar for Let it Go. Parents, be warned: The new song is catchy.
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"If history is any indicator, kids will go nuts," says Gad.
Life for the two princesses has changed in other ways. Olaf and Kristoff (along with Sven, the non-verbal reindeer) add to a highly unorthodox family. Their goofy portrait, inspired by the website AwkwardFamilyPhotos.com, hangs in the castle.
"There's a slight dorkiness to the painting," says Lee. "But it's the best thing they could all wish for, just that ordinary family feeling."
The Frozen landscape is also changed, as the kingdom embraces warm weather and Anna's summer solstice birthday. The directors promise other surprises as well. But the sister's rock-solid support for each other doesn't change from Frozen, which took in more than $400 million at the box office.
"We continue this story of these two sisters, who only had each other growing up together," says Gad. "They are still supporting each other. That's what this is about."