this cigarette stub is certainly remarkable. The
gentleman was bearded and moustached, you say?"

"Yes, sir."

"I don't understand that. I should say that only a clean-shaven man
could have smoked this. Why, Watson, even your modest moustache would
have been singed."

"A holder?" I suggested.

"No, no; the end is matted. I suppose there could not be two people in
your rooms, Mrs. Warren?"

"No, sir. He eats so little that I often wonder it can keep life in
one."

"Well, I think we must wait for a little more material. After all, you
have nothing to complain of. You have received your rent, and he is
not a troublesome lodger, though he is certainly an unusual one. He
pays you well, and if he chooses to lie concealed it is no direct
business of yours. We have no excuse for an intrusion upon his privacy
until we have some reason to think that there is a guilty reason for
it. I've taken up the matter, and I won't lose sight of it. Report to
me if anything fresh occurs, and rely upon my assistance if it should
be needed.

"There are certainly some points of interest in this case, Watson," he
remarked when the landlady had left us. "It may, of course, be
trivial--individual eccentricity; or it may be very much deeper than
appears on the surface. The first thing that strike one is the obvious
possibility that the person now in the rooms may be entirely different
from the one who engaged them."

"Why should you think so?"

"Well, apart form this cigarette-end, was it not suggestive that the
only time the lodger went out was immediately after his taking the
rooms? He came back--or someone came back--when all witnesses were out
of the way. We have no proof that the person who came back was the
person who went out. Then, again, the man who took the rooms spoke
English well. This other, however, prints 'match' when it should have
been 'matches.' I can imagine that the word was taken out of a
dictionary, which would give the noun but not the plural. The laconic
style may be to conceal the absence of knowledge of English. Yes,
Watson, there are good reasons to suspect that there has been a
substitution of lodgers."

"But for what possible end?"

"Ah! there lies our problem. There is one rather obvious line of
investigation." He took down the great book in which, day by day, he
filed the agony columns of the various London journals. "Dear me!" said
he, turning over the pages, "what a chorus of gr