The emergency drainage passage proved worse than Marcus expected.
The entrance appeared barely large enough for a man to crawl through. A broken stone grate hung from one side of the opening, while mineral deposits had narrowed the remaining gap over countless years. Cold water flowed steadily through the bottom of the passage, carrying black sediment deeper into the mountain.
Marcus crouched beside it and examined the interior through his night-vision goggles.
The tunnel descended at a sharp angle before curving west.
Its walls were smoother than the surrounding maintenance corridors. Instead of fitted stone blocks, the passage appeared to have been cut directly through solid rock with a level of precision that did not match the crude tools used elsewhere in the underground city.
There were no visible joints.
No support beams.
No cracks.
Cole knelt beside him.
"That doesn't look like a drainage tunnel."
"No."
Marcus reached out and ran a gloved hand across the wall.
