"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 Directly it had dropped in the grate, however, by means of this ring I assume that the weighted line was withdrawn, and the thing was only held by one slender thread, which sufficed, though, to draw it back again when it had done its work.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 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."