The forest was dark and quiet. Polly flew through the trees, following Astrid and Mikkel's path. The midnight sun barely reached through the branches.
"Astrid! Mikkel!" she called.
She heard a sharp breath ahead. Polly flew through some hanging plants and found them at the edge of a clearing. They stood frozen, staring.
The scene was strange. About twenty marathon runners stood in a semicircle, swaying together. Their eyes were open but empty, staring at the bunker entrance.
"Don't get too close," Astrid whispered. "Look at their shadows."
Polly looked down. The runners had no shadows at all. The sunlight passed right through them.
"That's impossible," Mikkel said quietly.
"Is it?" Astrid asked. "My grandmother told stories about this bunker. She said the Germans experimented here during the war. Something about the midnight sun."
Suddenly, a low humming filled the air. It vibrated through their bones. The runners began moving toward the bunker entrance.
"We have to stop them," Mikkel said.
"Wait," Astrid commanded. "Look at the entrance."
The bunker's doorway was shimmering like water. Through it, they could see another forest bathed in moonlight and stars.
"A portal," Polly whispered. "But to where?"
The first runner stepped through and vanished.
"The winter forest," Astrid said suddenly. "My grandmother mentioned it. The Germans thought they could use the midnight sun's energy to create a doorway."
Mikkel broke away and ran to a young woman runner. He grabbed her shoulders to wake her up.
Immediately, his eyes went blank. He began swaying like the others.
"No!" Astrid started forward, but Polly blocked her.
"Don't touch them! It's contagious!"
They watched helplessly as Mikkel joined the line moving toward the portal. The portal was growing bigger.
"It's expanding," Polly observed. "Soon it'll reach the marathon route."
Astrid's face became determined. "Then we stop it. My grandmother said they had a failsafe inside the bunker."
"Which means going through the portal," Polly finished.
Mikkel stepped through and vanished.
"Ready?" Astrid asked.
"Ready," Polly confirmed.
Together, they stepped toward the impossible doorway.
