Princes of the Apocalypse: Day 3 - Cave In!

Our adventurers found and rescued an 11-year-old boy who had been pinned under heavy stones as a punishment by his father, a town councilman, for failing to deliver a message.  He had been there quite some time and was dehydrated and hungry.  The group helped him and questioned him.  He declared himself to be a devoted "Believer" who worshipped the "Delvers", and was afraid his father would be angry that they had released him.  Fearing he would report their presence to his father, they kept him with them.  Then they explored further.  Two of them were almost captured by giant metal cages that fell from a tunnel ceiling.  Then they found and questioned another believer, an old man that they met just outside of the room of the Delvers.  Within, they found giant rocks that magically rose into the air when they stomped the floor.  Meanwhile, an unknown person snuck quickly out the back into another secret tunnel entrance and then triggered a cave-in to block it.  Josh, the druid, transformed into a small bug and passed through the rock pile.  He learned that the tunnel exited into the rock quarry they had passed when they first entered the town.  When he returned they all headed back to the entrance near Waelvur's Wagon shop.  The ground began to tremble and they just barely escaped back outside when a massive tremor shook the town.  Townsfolk ran outside in a panic, and then the screaming began near the center of town.