The party returned to the living quarters to examine the dusty mural. It depicted the three dwarven heroes Borum, Bandig, and Zaad. Close examination revealed a rune for the word eye (or old eye), and that the eyes on each dwarf could be moved to show as open or closed. After some experimenting you triggered a mechanism that opened the wall itself to reveal a passageway.
You explored the long tunnel and found it ran parallel to Bottletown and had many hidden holes observing the town itself. Further in this tunnel branched in two directions. You first went right to find a grand chamber with a large statue and a sealed gateway to the surface. When you entered the statue moved to regard you with its lifeless face. Warily you spoke to the statue who seemed to understand dwarven. It did not answer your questions with words but instead pointed to runes in the columns to return simple sentences – it explained that the surface was not safe, the gateway could not be opened, and that something that wasn’t a dwarf had come to the chamber recently and retreated.
Next you explored the other branch of the tunnel which seemed of unworked earth. It extended upwards and you found several snaking tunnels.This was the home of countless spiders of larger and larger sizes. Just as you were thinking to turn back a monstrous arachnid-humanoid who attacked with two giant spiders. The monster retreated after receiving a vicious wound while the party struggled to fell the spiders.
Wishing to return you retraced your way back to the living quarters and closed the hidden entrance. Mayor Urus was grateful for your return and hastened to restore the water stone to use. He rewarded you with coin and was perplexed as he heard you recount your journey.