Dungeon
The lobby guest book reveals that the location is the underground jailhouse for a religion.
In the left corridor, a large cut stone blocks the way, with only a narrow gap on either side. (The stone is buoyant in water!)
In the right corridor, a praying nun tells the adventurer and his ally that outlaws have taken shelter in an inner room; she invites them to capture them, in exchange for a powerful item and her assistance in a baptism in the fountain at the center of the dungeon. The ritual requires the blood of the outlaws.