I am pushed into a side cabin, the door is shut upon me, and here I am once more a prisoner in profound darkness.
I recognize the cabin the moment I enter it.

It is the place in which I spent so many long hours after our abduction from Healthful House, and in which I was confined until well out at sea off Pamlico Sound.
It is evident that Thomas Roch has been placed in a similar compartment.
A loud noise is heard, the banging of the lid as it closes, and the tug begins to sink as the water is admitted to the tanks.
This movement is succeeded by another--a movement that impels the boat through the water.
Three minutes later it stops, and I feel that we are rising to the surface again.
Another noise made by the lid being raised.
The door of my cabin opens, and I rush out and clamber on to the platform.
I look around and find that the tug has penetrated to the interior of Back Cup mountain.
This is the mysterious retreat where Count d'Artigas lives with his companions--out of the world, so to speak..