The human is an elder of Red Larch named Baragustas Harbuckler, a retired carpenter
"From time to time, the great stones change position when no one is watching. That is how they talk to us. They show us signs of coming danger and warn us when we make bad choices."
Several generations ago, stonecutters working in the quarries discovered the old tunnels, buried miners, and the weird phenomenon of the moving stones. At first those who found the place kept it secret because they hoped to find treasure within. No such treasure was ever found, but the conspiracy survived.
The Red Larchers who knew about the place came to Include the leading citizens of the town. They regarded the phenomenon as supernatural and portentous. They called themselves the Believers and referred to the miners entombed in the chamber as the Delvers. The Believers carefully observed the stones for messages in their movements, and they saw the Delvers as stern guardians watching over an ancient mystery.
Over the years, the Believers began to arrange events and opportunities in Red Larch to ensure that fellow Believers prospered. They became a secret town council and met to make hard decisions "for the good of all." People causing trouble in Red Larch were driven out of business, intimidated, or even murdered.
Several months ago, agents of the Cult of the Black Earth stumbled across the Tomb of Moving Stones, and an ambitious cult priest named Larrakh came to Red Larch to bring the Believers under the cult’s control. Unhindered by superstition, as the Believers are, he learned the secret of how to manipulate the moving stones. Larrakh now uses the stones to deliver "messages" that he interprets for the Believers, manipulating them to do the earth cult’s bidding.
The old carpenter knows much about the Believers’ influence in Red Larch over the years. The recent involvement with "the earth priests" who help them to understand the moving stones is something he idly mentions. He is quite intimidated by Larrakh, and more scared of the earth cultists than he is of the adventurers.
Larrakh is in the next room.