They retreated past the office through which they’d entered and continued along the corridor in the opposite direction, past more doors, until they arrived at a pile of broken furniture and collapsed walls. The wreckage included two metal doors that had broken loose from a frame. They stopped and looked down a shaft. Derek dropped to one knee, leaned over, and aimed his lamp into it. Up and down. “It’s an elevator,” he said. “Or it was.”

Hutch reached for him and grabbed his belt. “Careful.” She inched forward. The shaft overhead was clear for several floors. Below, she could see only a short distance before the shaft walls appeared to squeeze together.

Ken climbed across the fallen doors, continuing along the passageway. “Where you going?” asked Derek, who wanted everyone to stay in line.

“Looking for a stairway. There’s usually one near elevators.”

“Don’t forget we’re dealing with aliens here,” said Wally, from the ship.

“It probably doesn’t matter. The laws of physics are the same everywhere. And it looks as if—yes. There it is.”

“Stairs?” asked Derek. He got back up on his feet.

“Yes.”

Ken disappeared around a corner and Derek hurried after him.

“Holy cats,” Ken said. “You should see this.”

“What is it?” asked Wally.

Beth was climbing across the broken doors. But she lost her footing in the dark and crashed into Hutch. Hutch was pushed forward into the shaft, grabbing frantically for something to hold on to. But nothing was there, and the extra weight didn’t help. She teetered on the edge and would have fallen into the shaft had Beth, or someone, not grabbed her ankle. Her shin took a blow, and she was hanging head down as Beth screamed for help.

Then they had her other leg too. “I’ve got you,” said Derek. “Easy.”

They hauled her back up onto the broken doors, and she discovered she’d stopped breathing.

“I’m sorry,” Beth was saying. “Thank God.”

“You okay?” asked Derek. He was shining his lamp in her eyes.

“Yeah. I’m good.”

They dragged her farther from the shaft. “You’re the one,” Derek said, “who’s always telling everybody to be careful.”

“It was my fault,” said Beth. She’d worked her way past Hutch and was looking down over the edge. “My God, that wouldn’t have been good.”

“Would you please get away from there?” said Derek, grabbing her and hauling her back. “Are you people trying to get yourselves killed?”

“Hutch.” It was Wally again. “Try to be careful.” He paused. “Ken, could you please stand so I can see what’s the big deal about the stairway?”

Ken got out of the way so Wally could see all the way to the bottom. Or at least as far down as the light went. “That must be at least twenty floors down there,” he said. “There’s an entire city buried beneath the ice.”