"There's nothing worthwhile here, Argyle."
I kept my focus on the tunnel walls, ignoring Roan's complaints. We'd found the caves the day before, hidden by heavy foliage in the forest. It hadn't taken long to notice the support beams, hopefully set by pony hooves.
In the dim light of my lantern, I could just make out toolmarks. "Not if you don't look closely," I replied, ushering him over.
With his lantern, the marks were much easier to see. He rubbed a hoof over them. "A mine? Dug out, probably." The floor glittered in the light as Roan started to walk away.
He was right, and yet there had been no signs or supplies. Could it have been abandoned and picked clean? Was it older than I thought? We followed the tunnel into an open cavern, down another tunnel, past forks and into other caverns that held yet more tunnels. I tried to leave a trail while taking notes.
"It's still fascinating, to see the type of materials we were looking for," I said, before my hoof caught on something and I tumbled forward. We both screamed at once.
There were corpses, two of them, but not skeletal remains or decomposing bodies. Instead, their fur had shed and their skin dehydrated as it clung to their bones. Curiosity took hold of me; they felt fragile, as if they would crumble into dust under too much pressure.
Most exciting, I regret, was that they were not earth ponies like us. One had a horn and the other curled, featherless wings.
"How long do you think they've been here?" I asked, but Roan was already tugging me away from them and back the way we had come.
"That doesn't matter!" Roan shouted, words echoing through the mines. "It's proof enough they were here, right? That this was some 'united' pony mine?" I could hear the mixture of excitement and fear in his voice.
"I-I suppose, but… they could have wandered in here, right? If they're…" I had to swallow a lump in my throat, but it did nothing to calm the knots forming in my stomach. "If they're recent, then it's not conclusive."
I looked down at the unicorn, face twisted and suspended in terror; on his haunches was a saddle bag, covered in dust and filled with holes. While Roan looked around, I bent down and opened it, pulling out what looked like a journal, covered in rot and filled with cracked and yellow pages.
The writing was hard to make out, faded in spots and with entire chunks of pages missing, but I could still find dates long before our own and around what I assumed was the middle of Princess Twilight’s rule. Here and there I saw figures and diagrams, of what I didn't know. The last entry was scrawled in hurried, heavy strokes.
"We have to bury it deep. However deep we dug, bury it deeper."
I repeated the words aloud, Roan peering over my shoulder. There was the sound of pebbles, moving beneath his hooves I thought. Then I noticed they came from ahead of us.
I shut the journal slowly, looking into the deep darkness beyond our lanterns. I felt something staring back at me, even if I saw nothing. "Roan," I whispered. He was already trying to help me stand up.
Something dislodged itself from the wall, a shower of small stones skidding along the floor. I heard bones cracking and a deep breath like a dragon's of ages past. A tendril or tongue or something slithered out from the dark and wrapped itself around the unicorn's horn before pulling it out of the light.
We turned and ran before an ear-piercing screech echoed through the tunnels. Heart pounding in my chest I galloped, turning and following any sign of the path I had left for us. Whatever followed thundered through the tunnel; I heard the breaking of stone and crunching of wooden pillars with every turn.
We were close, I knew we had to be close. I heard Roan gasp, his lantern shatter. Skidding to a stop, I turned to look back; he was just on the edge of my own light. He held onto one hind leg with his hooves. I saw red and white.
As soon as I tried to move to help him, my body froze. My mind screamed at me that if I did, I would die. I couldn't fight it, left starring at my friend and the deep, impenetrable black.
The heavy steps became slower. There was a growl and hiss, followed by what I thought for a moment was singing. It sounded like her, even though I knew she was gone.
Roan turned and looked into the black. His eyes went wide, his mouth agape in awe. And then I saw him smile and laugh. For a moment, I thought I saw the glint of a unicorn's horn, but it was gone when I blinked.
My body relaxdd and as I ran to Roan, lifted him onto my back, and then turned to run away. I kicked at every support I could find as hard as I could. When I reached the entrance, I heard them crack followed by tumbling of rocks. Dust billowed up behind us as we came out into the forest.
"Roan was never the same. He never talked about anything but the mines, and tried to run away from Maretime Bay a dozen times to go back there. Eventually he couldn't move. The doctors said his body kept atrophying, but they couldn't find a solution.
"Sunny, whatever you try to do on your own, wherever you go looking for anything, please don't go there. The map is here only to show you where never to go."
Sunny closed her father's journal, unfurling the small map she had found within. To the northwest of Maretime Bay, deep in the forests, was a circled patch of hill and rock with three words: Bury it deeper.