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  Directly it had dropped in the grate, however, by means of this ring I assume that the weighted line was withdrawn, and the thing was only held by one slender thread, which sufficed, though, to draw it back again when it had done its work.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 the room.  “What is your theory respecting this creature—­ what shape, what color—?”

“It is something that moves rapidly and silently.  I will venture no more at present, but I think it works in the dark.  The study was dark, remember, save for the bright patch beneath the reading-lamp.  I have observed that the rear of this house is ivy-covered right up to and above your bedroom.  Let us make ostentatious preparations to retire, and I think we may rely upon Fu-Manchu’s servants to attempt my removal, at any rate—­if not yours.”

“But, my dear fellow, it is a climb of thirty-five feet at the very least.”

“You remember the cry in the back lane?  It suggested something to me, and I tested my idea—­successfully.  It was the cry of a dacoit.  Oh, dacoity, though quiescent, is by no means extinct.  Fu-Manchu has dacoits in his train, and probably it is one who operates the Zayat Kiss, since it was a dacoit who watched the window of the study this evening.  To such a man an ivy-covered wall is a grand staircase.”

The horrible events that followed are punctuated, in my mind, by the striking of a distant clock.  It is singular how trivialities thus assert themselves in moments of high tension.  I will proceed, then, by these punctuations, to the coming of the horror that it was written we should encounter.

The clock across the common struck two.

Having removed all traces of the scent of the orchid from our hands with a solution of ammonia Smith and I had followed the programme laid down.  It was an easy matter to reach the rear of the house, by simply climbing a fence, and we did not doubt that seeing the light go out in the front, our unseen watcher would proceed to the back.

The room was a large one, and we had made up my camp-bed at one end, stuffing odds and ends under the clothes to lend the appearance of a sleeper, which device we also had adopted in the case of the larger bed.  The perfumed envelope lay upon a little coffee table in the center of the floor, and Smith, with an electric pocket lamp, a revolver, and a brassey beside him, sat on cushions in the shadow of the wardrobe.  I occupied a post between the windows.