on?"

"The fact is," I said, "I am in a rather awkward dilemma, and I want you
to tell me what you think I ought to do."

Thorndyke paused in the act of refilling my cup and glanced at me with
unmistakable anxiety.

"Nothing of an unpleasant nature, I hope," said he.

"No, no; nothing of that kind," I answered with a smile as I interpreted
the euphemism; for "something unpleasant," in the case of a young and
reasonably presentable medical man is ordinarily the equivalent of
trouble with the female of his species. "It is nothing that concerns me
personally at all," I continued; "it is a question of professional
responsibility. But I had better give you an account of the affair in a
complete narrative, as I know that you like to have your data in a
regular and consecutive order."

Thereupon I proceeded to relate the history of my visit to the
mysterious Mr. Graves, not omitting any single circumstance or detail
that I could recollect.

Thorndyke listened from the very beginning of my story with the closest
attention. His face was the most impassive that I have ever seen;
ordinarily as inscrutable as a bronze mask; but to me, who knew him
intimately, there was a certain something--a change of colour, perhaps,
or an additional sparkle of the eye--that told me when his curious
passion for investigation was fully aroused. And now, as I told him of
that weird journey and the strange, secret house to which it had brought
me, I could see that it offered a problem after his very heart. During
the whole of my narration he sat as motionless as a statue, evidently
committing the whole story to memory, detail by detail; and even when I
had finished he remained for an appreciable time without moving or
speaking.

At length he looked up at me. "This is a very extraordinary affair,
Jervis," he said.

"Very," I agreed; "and the question that is agitating me is, what is to
be done?"

"Yes," he said, meditatively, "that is the question; and an uncommonly
difficult question it is. It really involves the settlement of the
antecedent question: What is it that is happening at that house?"

"What do you think is happening at that house?" I asked.

"We must go slow, Jervis," he replied. "We must carefully separate the
legal tissues from the medical, and avoid confusing what we know with
what we suspect. Now, with reference to the medical aspects of the case.
The first question that confronts us is that of sleeping sickness, or
ne