"Well," he replied, "we have good evidence to show that the assassin possesses an almost Napoleonic capacity for working by the time-table. Witness the employment of Constable Bolton in the Red House affair--which showed that our man was perfectly acquainted with the movements of the officer on that beat and timed his scheme accordingly. Very well ... having laid the telephone trap in your ante-room--did our man hurry away and make the call _in person_, which brought Coverly to the 'phone?--or did he remain watching the house and give the signal to _some one else_ to do it?" "I cannot imagine, Gatton. Nor does the point strike me as important." "No?" said Gatton, smiling triumphantly. "Then I must explain. Whereas, in the Red House, the scheme worked _automatically_--for the time of Sir Marcus's arrival was _fixed_--in the present instance, some one had to watch for _your_ return from the mythical appointment!" "For _my_ return?" "Unquestionably! This scheme was arranged for your benefit, Mr. Addison. Unknowingly, poor Coverly saved you from a dreadful fate at the price of his own life! You see, they did not know that Coverly was coming here! Now, it will not have escaped your attention that he wore a soft felt hat, a light overcoat, and carried a black cane. So did _you_ when you went out to keep the appointment made by the assassin!" He paused, staring at me hard, and: "Whoever was watching for your return," he said solemnly, "mistook Coverly for you! The moment that Coates drove away, the signal was given. It _must_ have been. We were back here a few minutes later, _Now_ do you see?" "I do not, Gatton! What are you driving at?" "At this: The telephone call _must_ have been made from somewhere in the immediate neighborhood! There wasn't time to do it otherwise. And there is no public call office within a mile _which is open after seven o'clock!"_ "Good heavens!" I cried. "At last I understand!" Gatton looked at me, smiling in grim triumph; and: "Dr. Damar Greefe has a residence somewhere within a quarter-mile radius of this house!" he declared. "He has betrayed himself! Then--look here." Unscrewing the front of the mouthpiece of the false telephone, he took out the strip of cardboard upon which my number was written, turned it over ... and there upon the back was another number! "Just look up Dr. Brown-Edwards," he said. "He was the last occupant of the Red House, and may still be in the book." Grasping the purpose of his inquiry, excitedly I did as he directed; and there sure enough the number appeared! "The identical instrument that was used at the Red House!" cried Gatton. "Note the artistic finish with which even the _correct_ exchange numbers are looked up!" I sank back in my chair, silent, appalled at the perverted genius of this fiend whom we were pitted against in a life-or-death struggle. But presently: