Wait, what's that on the floor?

As you walk through the doorway, you look back into the room one last time. Wait, what was that? As the sunlight came through the door, you notice it glinted peculiarly off one section of the floor. You close the door, go back and get on your hands and knees where you noticed the glint. The floor is made of some strange white material, you can't quite tell what, and seems quite seamless.

You have an idea and go back and reopen the door, leaving it open this time. Sure enough, that glint is back, and this time you use it to find an otherwise imperceptable seam in floor. You never would have found it if the sun had not been at exactly that angle to come in through the doorway. Luckily you have long and strong fingernails and can just wedge one into the seam. You pry at it, and your nail breaks, but also the floor gives a little. Trying again with the nail from your other hand, you get it. The covering of the floor gives a little, as before, then swings up perpendicular to the floor, revealing a hidden trap door.

Sticking your head down into the circular hole in the floor and peering around, you see a ladder attached to the wall descending down into darkness. You are scared, but curious. Gathering your courage, you swing yourself onto the ladder and head down. Just as you start to think it will go on forever, you see a light beneath you revealing a new room. You follow the ladder down till it ends in this room, then turn around to see your new surroundings.