Lost in Bogfield Swamp and nightfall approaching, the party finds a slightly higher piece of ground. There are low walls from an ancient ruin to provide cover during the night. While searching for some dry wood, a trap door is found under the grass.
The first level down contains 2 waterlogged storage rooms. Next level down contains a room with a sacrificial altar wherein the blood is allowed to drip down to another level down below through a grate in the floor. On the walls in the room before the next set of stairs down are four painted murals. Progress on the next level is impeded by a locked door without any visible means of opening it. Upon further inspection a slight indentation is seen in the tile work on the door. Going back to the room with the murals they see that in a picture is a soldier holding a trident and upon touching that part of the picture the head of the trident comes off. Going back to the door the trident fits into the indentation and the door opens.