I had closed the window to exclude the yellow mist, but subconsciously I was aware of its encircling presence, walling me in, and now I found myself in such a silence as I had known in deserts but could scarce have deemed possible in fog-bound London.

A quick footstep approached the door, and there came a muffled rapping upon the panel.

I leapt across the room and threw the door open. Nayland Smith stood before me.

"If I am to believe what the Chief has told me today," he said, "strange things are ahead of us."

I stared at him wonder-stricken. . . .