sma. You know, sir, it's hard to explain just the way
I felt about it--but it all amounts to this: I was glad to get
outside!"

Dr. Cairn stood up and began to pace about the room, his hands locked
behind him.

"To-night," he rapped suddenly, "what occurred to-night?"

"To-night," continued his son, "I got in at about half-past nine. I
had had such a rush, in one way and another, that the incident had
quite lost its hold on my imagination; I hadn't forgotten it, of
course, but I was not thinking of it when I unlocked the door. In fact
I didn't begin to think of it again until, in slippers and
dressing-gown, I had settled down for a comfortable read. There was
nothing, absolutely nothing, to influence my imagination--in that way.
The book was an old favourite, Mark Twain's _Up the Mississippi_, and
I sat in the armchair with a large bottle of lager beer at my elbow
and my pipe going strong."

Becoming restless in turn, the speaker stood up and walking to the
fireplace flicked off the long cone of grey ash from his cigar. He
leant one elbow upon the mantel-piece, resuming his story:

"St. Paul's had just chimed the half-hour--half-past ten--when my pipe
went out. Before I had time to re-light it, came the damnable smell
again. At the moment nothing was farther from my mind, and I jumped up
with an exclamation of disgust. It seemed to be growing stronger and
stronger. I got my pipe alight quickly. Still I could smell it; the
aroma of the tobacco did not lessen its beastly pungency in the
smallest degree.

"I tilted the shade of my reading-lamp and looked all about. There was
nothing unusual to be seen. Both windows were open and I went to one
and thrust my head out, in order to learn if the odour came from
outside. It did not. The air outside the window was fresh and clean.
Then I remembered that when I had left my chambers in the afternoon,
the smell had been stronger near the door than anywhere. I ran out to
the door. In the passage I could smell nothing; but--"

He paused, glancing at his father.

"Before I had stood there thirty seconds it was rising all about me
like the fumes from a crater. By God, sir! I realised then that it was
something ... following me!"

Dr. Cairn stood watching him, from the shadows beyond the big table,
as he came forward and finished his whisky at a gulp.

"That seemed to work a change in me," he continued rapidly; "I
recognised there was something behind this disgusting manifes