Chapter 29 - The Cavern of Voices

The roar of gunfire inside an enclosed limestone cave was deafening. The sound didn't dissipate; it ricocheted off stone walls, creating a disorienting wall of concussive pressure that felt like physical blows against our temples.
"Move along the rail bed!" I shouted, grabbing Michael’s coat and shoving him toward the narrow shadow beneath an overhang of flowstone.
Director Vance returned fire with mechanical precision, using the rhythmic muzzle flashes of the contractors to aim. A scream echoed over the sound of the river as one of the contractors went down, his rifle clattering against the iron tracks.
Michael dropped to one knee behind an overturned ore cart, chambering another shell into the Winchester. "Dad, they’ve got night vision! In the dark, they have every advantage!"
"Not in this cave, they don't!" I shouted back.
I reached into my pocket and pulled out Margaret’s brass whistle—the high-pitched signal whistle she used to call the sheep down from the high meadow. In the open air, it was just a sharp sound. But down here, surrounded by hundreds of thousands of dormant bats resting in the high domes of the Blackwood system, it was a seismic trigger.
I put the brass whistle to my lips and blew with everything I had.
The piercing, ultrasonic shriek ripped through the cavern, echoing across millions of crystalline formations.
For two seconds, there was silence.
Then, the ceiling came alive.
A sound like an approaching freight train filled the cavern as tens of thousands of gray bats detached from the limestone roof in a blind, terrified panic. The air became a hurricane of leathery wings, high-pitched screeching, and swirling wind.
The contractors screamed in confusion. Through their night-vision goggles, the sudden swarm of tens of thousands of warm bodies created an blinding blizzard of thermal static and green light overload. One man tore his goggles off in terror, firing blindly into the air, while the other fell backward off the narrow ledge, landing hard onto the jagged shale bank below.
"Now! Run!" Vance yelled, grabbing my arm.
We sprinted through the blinding blizzard of wings, keeping our hands on the cold iron rail of the ore track to guide our feet. We bypassed the bridge entirely, scrambling over the narrow natural rock arch that Margaret had mapped fifty years ago.
Behind us, a dull, terrifying thud reverberated through the very bedrock beneath our feet.
*BOOM.*
The charges in bore-hole three had detonated.
The cavern roof groaned—a sound so deep, so primal, that it felt like the earth itself was splitting in two. Cracks three feet wide raced across the ceiling, releasing torrents of crushed limestone and ancient gravel.
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"The whole mountain is coming down!" Michael yelled, lunging forward and pushing me through a low, narrow opening at the end of the rail tunnel.
We tumbled out into the cold night air just as a deafening roar collapsed the cavern entrance behind us, sealing the Blackwood underground chambers forever under ten thousand tons of shattered rock.