empt to kill Sir Crichton--you recall that he thought
there was something concealed in his study on a previous
occasion?--Fu-Manchu hit upon the perfumed envelopes. He may have a
supply of these green orchids in his possession--possibly to feed the
creature."

"What creature? How could any kind of creature have got into Sir
Crichton's room tonight?"

"You no doubt observed that I examined the grate of the study. I found
a fair quantity of fallen soot. I at once assumed, since it appeared
to be the only means of entrance, that something has been dropped down;
and I took it for granted that the thing, whatever it was, must still
be concealed either in the study or in the library. But when I had
obtained the evidence of the groom, Wills, I perceived that the cry
from the lane or from the park was a signal. I noted that the
movements of anyone seated at the study table were visible, in shadow,
on the blind, and that the study occupied the corner of a two-storied
wing and, therefore, had a short chimney. What did the signal mean?
That Sir Crichton had leaped up from his chair, and either had received
the Zayat Kiss or had seen the thing which someone on the roof had
lowered down the straight chimney. It was the signal to withdraw that
deadly thing. By means of the iron stairway at the rear of
Major-General Platt-Houston's, I quite easily, gained access to the
roof above Sir Crichton's study--and I found this."

Out from his pocket Nayland Smith drew a tangled piece of silk, mixed
up with which were a brass ring and a number of unusually large-sized
split-shot, nipped on in the manner usual on a fishing-line.

"My theory proven," he resumed. "Not anticipating a search on the
roof, they had been careless. This was to weight the line and to
prevent the creature clinging to the walls of the chimney. Directly it
had dropped in the grate, however, by means of this ring I assume that
the weighted line was withdrawn, and the thing was only held by one
slender thread, which sufficed, though, to draw it back again when it
had done its work. It might have got tangled, of course, but they
reckoned on its making straight up the carved leg of the writing-table
for the prepared envelope. From there to the hand of Sir
Crichton--which, from having touched the envelope, would also be
scented with the perfume--was a certain move."

"My God! How horrible!" I exclaimed, and glanced apprehensively into
the dusky shadows of th