Please face about with eyes to the front window.

Yes, so; now do not look around until I tell you." I heard her cross the room, her skirts rustling slightly, and then the faint clicking of some delicately adjusted mechanism.

As this sound ceased, her voice again spoke.
"Now, Major, the way is opened for a safe retreat.

Behold what has been accomplished by the genii of the lamp." She was standing at one side of what had been the fireplace, but now the entire lower portion of the great chimney had been swung aside, revealing an opening amply large enough for the entrance of a man.

I took one step forward to where I could perceive the beginning of a narrow winding stair leading down into intense blackness.