ond me at present, as indeed is the whole business of the
murder. Whether we shall ever know more I can't guess, but the matter is
deep--deep and difficult and dark. As to the mark itself, that seems to
have been impressed from an engraved stamp of some sort. It is a plain
equilateral triangle in red outline, measuring about an inch on each
side. It is in a greasy, sticky sort of red ink, which may be smeared,
but is very difficult, if not impossible, to rub away. What it means I
can't at present conjecture. I have told you my reasons for not thinking
it the sign of any gang of criminals. But whose sign is it? Surely not
that of some self-constituted punisher of crime? For such a person, with
no risk to himself, could have handed Denson over to the police, if he
knew of his offence. Can he have been murdered by an accomplice? But he
used no accomplice; if one thing is plain in all that story of the
stolen diamonds it is that Denson did the thing wholly by himself.
Besides, an accomplice would have taken the keys and have gone and
secured the diamonds for himself; else why the murder at all? But no
keys were taken--nothing was taken, as far as we can tell. And why was
the body placed in that conspicuous position? It is pretty certain that
the crime cannot have happened where the body was found--somebody must
have heard or seen a struggle in such a place as that. As it is, I
should say, the body was probably brought quietly to the spot in a cab,
or some such conveyance.

"But mystery envelops this crime everywhere. So far as I can see, there
is no clue whatever beyond the Red Triangle, which, as yet, I cannot
understand. The strangling points to the murder being committed by a
powerful man, certainly, and it is a form of crime that may have been
perpetrated silently. But beyond that I can see nothing. The apparent
motivelessness of the thing makes the mystery all the darker, and the
circumstances we are acquainted with, instead of helping us, seem to
complicate the puzzle.

"What was it that Denson feared when he left those diamonds behind him,
when he might have carried them away? And why should he fear it in
daytime and not at night, since it would seem plain that he meant to
have returned for the stones at night? Where did he go to disguise
himself yesterday--we know it was not in his lodgings--and where has he
left the clothes he discarded?"

All these doubts and mysteries were destined to be cleared up, in more
or