"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!"