Whoo. The strange sound came from outside theopen window.

Jack opened his eyes in the dark.

The sound came again. Whoo.

Jack sat up and turned on his light. He put on hisglasses. Then he grabbed the flashlight from his tableand shone it out the window.

A white snowy owl was sitting on a treebranch.

"Whoo," the owl said again. Its large yellow eyeslooked right into Jack's.

What does he want? Jack wondered. Is he a sign,like the rabbit and the gazelle?

A long-legged rabbit and a gazelle had led Jack andAnnie to the magic tree house for their last twoadventures.

"Whoo.""Wait a second," Jack said to the owl. "I'll getAnnie."Jack's sister, Annie, always seemed to know whatbirds and animals were saying.

Jack jumped out of bed and hurried to Annie'sroom. She was sound asleep.

Jack shook her and she stirred.

"What?" she said.

"Come to my room," whispered Jack. "I thinkMorgan's sent another sign."In a split second, Annie was out of bed.

She hurried with Jack to his room.

Jack led her to the window. The snowy owl wasstill there.

"Whoo," said the owl. Then he raised his whitewings and took off into the night.

"He wants us to go to the woods," said Annie.

"That's what I thought," said Jack. "Meet youdownstairs after we get dressed.""No, no. He says go now. Right now," said Annie.

"We'll have to wear our pajamas.""I have to put on my sneakers," said Jack.

"Okay, I'll put on mine, too. Meet you downstairs,"said Annie.

Jack pulled on his sneakers. He threw his notebookinto his backpack. Then he grabbed his flashlight andtiptoed downstairs.

Annie was waiting at the front door. They silentlyslipped outside together.

The night air was warm. Moths danced around theporch light.

"I feel weird," said Jack. "I'm going back to put onsome real clothes.""You can't " said Annie. "The owl said right now."She jumped off the porch and headed across theirdark yard.

Jack groaned. How did Annie know exactly whatthe owl said? he wondered.

Still, he didn't want to be left behind. So he took offafter her.

The moon lit their way as they ran down theirstreet. When they entered the Frog Creek woods, Jackturned on his flashlight.

The beam of light showed shadows and swayingbranches.

Jack and Annie stepped between the trees. Theystayed close together.

"Whoo"Jack jumped in fear.

"It's just the white owl," said Annie. "He'ssomewhere nearby.""The woods are creepy," said Jack.

"Yeah," said Annie. "In the dark, it doesn't even feellike our woods."Suddenly the owl flapped near them.

"Yikes!" said Annie.

Jack shone his flashlight on the white bird as it roseinto the sky. The owl landed on a tree branch--'rightnext to the magic tree house.

And there was Morgan le Fay, the enchantresslibrarian. Her long white hair gleamed in the beam ofJack's flashlight.

"Hello," Morgan called softly in a soothing voice.

"Climb up."Jack used his flashlight to find the rope ladder.

Then he and Annie climbed up into the tree house.

Morgan was holding three scrolls. Each one heldthe answer to an ancient riddle that Jack and Anniehad already solved.

"You have journeyed to the ocean, the Wild West,and Africa to find the answers to these three riddles,"said Morgan. "Ready for another journey?""Yes!" said Jack and Annie together._Morgan pulled a fourth scroll from the folds of herrobe. She handed it to Annie.

"After we solve this riddle, will we become MasterLibrarians?" asked Annie.

"And help you gather books through time andspace?" said Jack.

"Almost..." said Morgan.

Before Jack could ask what she meant, Morganpulled out a book and gave it to him. "For yourresearch," she said.

Jack and Annie looked at the book's title:

ADVENTURE IN THE ARCTIC.

"Oh, wow, the Arctic!" said Annie.

"The Arctic?" said Jack. He turned to Morgan. "Areyou serious?""Indeed I am," she said. "And you must hurry.""I wish we could go there," said Annie, pointing atthe cover.

"Wait--wait a minute--we'll freeze to death!" saidJack.

"Fear not," said Morgan. "I am sending someone tomeet you."The wind started to blow.

"Meet us? Who?" said Jack.

"Whoo?" said the snowy owl. Before Morgan couldanswer, the tree house started to spin.

It spun faster and faster.

Then everything was still.

Absolutely still.