Archive MT-205 · Epistolary horror

Below Marker 12

Marker 12 is the end of the public route.

Published 17 August 2026

It is also the deepest point marked on every official map of Blackstone Caverns.

So when a missing tourist is heard calling for help from somewhere beneath it, rescuers assume the cave’s strange acoustics are misleading them.

Then her body is discovered near the entrance. She had already been dead while they were listening to her voice.

Eleven months later, another visitor disappears. Search teams again hear someone calling from below Marker 12… calmly, patiently, and in the voice of a man who should not be there.

A new geological survey uncovers descending fissures, vast unmapped chambers and evidence that animals have been travelling deep beneath the known cave system for generations. As the expedition moves lower, the voices multiply. They call rescuers by name. They imitate the dead. Sometimes, they imitate people who are still alive.

And something in the darkness appears to be learning.

Told through incident reports, emergency calls, survey notes, radio transcripts and recovered recordings, Below Marker 12 is an epistolary descent into a place that was never empty. It should never have been opened.

If you hear someone you love calling from the dark, do not answer.