Elsa, who was eight years old, grumbled and ducked under the covers. "Anna, go back to sleep."

The girl jumped out of bed and tiptoed across the room to wake her older sister. "Elsa, Elsa!" she said urgently. "Wake up!"

In a grassy valley next to a deep fjord, the castle of Arendelle lay silent in the night. The bright luster of the northern lights danced across the windows, waking a small girl. She sat up and grinned to see the wonderful green light.

But Anna wouldn't give up. "I just can't. The sky's awake, so I'm awake, and so we have to play," she said. "Do you want to build a snowman?"

Elsa's eyes popped open. That got her attention. The girls were the daughters of Arendelle's king and queen, and the best of friends. Elsa couldn't resist Anna's begging. The sisters ran down the hallway in their nightgowns, laughing as they hurried along. Entering the Great Hall, where all the royal balls were held, they turned to each other.

"Yes, yes!" Anna cried, reaching out to tickle her sister.

"Are you ready?" Elsa asked, smiling.

Anna clapped happily. She knew that her sister had a very special talent: she could create snow and ice, even in the middle of summer!

Elsa laughed at the lopsided snowman. "Hi, I'm Olaf," she said in a deep voice, pretending to be the snowman. "And I like warm hugs."

Elsa giggled, and suddenly, snowflakes seemed to burst in a flurry from her hands!

With a twirl and a wave of her hands, Elsa magically summoned her icy powers. Quickly, she filled the Great Hall with mounds of fluffy snow, turning it into a winter playground. Then she stomped her feet and ice swept across the floor. She laughed to see little Anna hopping around joyfully.

The girls danced around their funny snowman. Then Elsa gathered her icy magic and made a swooping ice slide. Anna squealed with delight. She climbed to the top of the slide, then zoomed down and soared up again along the icy curve. Elsa quickly created another slide to catch Anna as she came down. The little girl gained speed and was tossed upward again. Elsa had to work fast to keep pace with Anna. She kept making more slides so her sister could stay aloft as she flew around the room.

Together, they went to work building their snowman. Anna did her best to roll out the snowman's body. Then she ran to get a carrot for the nose. "Snowman!" she exclaimed proudly.

Anna gasped and fell to the ground, unconscious. "Anna!" Elsa shouted, running to her sister. She lifted Anna up and felt her cold, shivering body. A lock of Anna's hair had turned pure white where the magic had hit it. "Mama! Papa!" Elsa cried desperately.

But Anna was having fun. The little princess was fearless, jumping and sliding to each new slide as quickly as Elsa made it. Elsa raised her hand to create the next slide, but suddenly, her foot slipped. As she stumbled, her magic went awry. Her frozen blast caught the side of Anna's head, right through her curls.

As she called for help and her worry increased, icicles formed on the ceiling, and frozen spikes grew tall around the girls.

"I'm sorry," Elsa replied in distress. "I didn't mean it!"

"Anna, slow down," Elsa said, starting to get worried. "It's too high!"

The king and queen burst into the Great Hall to find their daughters huddled in a frozen landscape. They knew that Elsa had a special ability to create ice, but this was more than they'd ever seen. "Elsa," the king cried. "This is getting out of hand!"

"Anna!" the queen gasped, and ran toward her little girl.