An exclamation of annoyance broke from Nick Carter’s lips.  
“I didn’t give him credit for so much cunning,” he thought. “But hanged if I see why he should have felt it necessary to skulk away in that fashion. It can’t be possible that he suspects me, and I don’t know of any reason why Crawford should not know of his going out.”
 
He concluded on the whole that it was probably an evidence of the instinctive slyness of the mentally affected, and nothing more. Further, he concluded that Stone had probably turned along the corridor in the other direction, used the servants’ stairs, and left by one of the side exits. Of course, it was possible that his demented brain had urged him on to the use of the fire escape. The more he thought about it, the more he became convinced that the latter supposition was nearer the truth. It would be just like a man in Stone’s condition to resort to such a ruse.
 
The miner’s disappearance had been a great disappointment to the detective. When he had discovered from the shadows on the drawn shade that Stone was going out, his hopes had risen. He had counted on following the man and getting some line on his movements, but now that was out of the question.
 
He knew that it was useless to follow Stone after that delay, but as a result of a few seconds’ deliberation, he decided not to let the chance slip altogether. Donning his lightweight overcoat, and buttoning it up to his chin in order to conceal the conspicuous expanse of white shirt front—which might draw undesired attention—he softly raised the sash of his window and stepped out on the wide sill. The fire escape did not lead down directly past his room, but one end of the iron platform came within two or three feet of the window on the right side.
 
It was the simplest matter in the world for Nick to grasp the rail and to hoist himself over.
 
The windows of the hotel were supplied with a novel patent catch which automatically fastened both the upper and lower sashes when the latter was pulled down. Nick, therefore, took pains to leave his window open after passing through it.
 
It was this peculiarity of the windows which had brought him out on the fire escape. He knew that if Stone had his wits about him, and had departed by that route, he must have left his window open or fixed it in some way to prevent his being locked out. It was to find if such precautions had been taken that he had made the effort.
 
When he approached Stone’s window, the lower sash seemed to be closed, but a closer inspection revealed that a narrow wedge of wood had been inserted, leaving a half-inch crack at the bottom—just enough to permit a man’s fingers to get a purchase on the sash and raise it.
 
It was only a trivial thing, but it gave Nick a clew to what was going to happen.
 
“He didn’t want the window to be locked by accident,” he mused, “and so he placed the wedge there. That means he’s going to come back this way, and it seems to me also that he wishes his partner to think he has been in all the evening—probably that he has gone to bed. It looks as if things were coming to a head.”
 
There was a cluster of small lights on a pole in the middle of the big courtyard, and the shades of many of the windows opening on it were up. It was light enough, therefore, for the detective to see with reasonable clearness—and to be seen, if any one happened to look in his direction.
 
He leaned over the rail and peered down. He was only at the level of the second floor, but the pavement of the courtyard was flush with the basement; therefore, two floors beneath him. He looked to see if the lowest ladder of the fire escape was in place but saw that it was not.
 
“Stone probably dropped from the last platform,” he concluded. “It wouldn’t have been anything for a man of his active habits. I wonder how he expects to get back, though. By George! There’s a painter’s ladder lying on the pavement on the other side of the court. Such things never ought to be left around. The sight of that ladder would tickle a thief to death. Stone probably saw it and made his plans accordingly.
 
“He expects to use it to reach the lower platform, but I&r............