They were not long in coming. I had hardly settled in my chair before I was conscious of a thick, musky odour, subtle and nauseous. At the very first whiff of it my brain and my imagination were beyond all control. A thick, black cloud swirled before my eyes, and my mind told me that in this cloud, unseen as yet, but about to spring out upon my appalled senses, lurked all that was vaguely horrible, all that was monstrous and inconceivably wicked in the universe. Vague shapes swirled and swam amid the dark cloud-bank, each a menace and a warning of something coming, the advent of some unspeakable dweller upon the threshold, whose very shadow would blast my soul. A freezing horror took possession of me. I felt that my hair was rising, that my eyes were protruding, that my mouth was opened, and my tongue like leather. The turmoil within my brain was such that something must surely snap. I tried to scream and was vaguely aware of some hoarse croak which was my own voice, but distant and detached from myself. At the same moment, in some effort of escape, I broke through that cloud of despair and had a glimpse of Holmes’s face, white, rigid, and drawn with horror - the very look which I had seen upon the features of the dead. It was that vision which gave me an instant of sanity and of strength. I dashed from my chair, threw my arms round Holmes, and together we lurched through the door, and an instant afterwards had thrown ourselves down upon the grass plot and were lying side by side, conscious only of the glorious sunshine which was bursting its way through the hellish cloud of terror which had girt us in. Slowly it rose from our souls like the mists from a landscape until peace and reason had returned, and we were sitting upon the grass, wiping our clammy foreheads, and looking with apprehension at each other to mark the last traces of that terrific experience which we had undergone.

“Upon my word, Watson!” said Holmes at last with an unsteady voice, “I owe you both my thanks and an apology. It was an unjustifiable experiment even for one’s self, and doubly so for a friend. I am really very sorry.”

“You know,” I answered with some emotion, for I had never seen so much of Holmes’s heart before, “that it is my greatest joy and privilege to help you.”

He relapsed at once into the half-humorous, half-cynical vein which was his habitual attitude to those about him. “It would be superfluous to drive us mad, my dear Watson,” said he. “A candid observer would certainly declare that we were so already before we embarked upon so wild an experiment. I confess that I never imagined that the effect could be so sudden and so severe.” He dashed into the cottage, and, reappearing with the burning lamp held at full arm’s length, he threw it among a bank of brambles. “We must give the room a little time to clear. I take it, Watson, that you have no longer a shadow of a doubt as to how these tragedies were produced?”

“None whatever.”