The hatch to the tunnel closed slowly behind them. Star and Jameson stood side by side, rifles held out and down in front of their chests, ready to be brought into firing position if any threat appeared in front of them. But nothing appeared in front of them. The heavy see-through door at their backs, that didn’t look heavy at all, chinked shut with a slightly hollow and deep finality. Star glanced over her shoulder. There was no spinner mounted on the inside of the door. How could it be opened from inside the tunnel? But that was a possible worry for later, she realized, as she snapped her attention back to staring into the hypnotic round perfection of the slightly bending tunnel which seemed to disappear out into a distant dot of infinity.

She let her eyes stray around her. The tunnel surface wasn’t flat. The entire tube was rounded, with no hint of how supplies could be hauled, one way or the other. There were no tracks or overhead trolley slots. There were no lights. The only light bled out of the walls themselves. The light was faint and white, and the tunnel was moving. Star realized that while both she and Jameson had remained rooted to their spots, the tunnel had started moving.