The floor had fallen away beneath his feet, and he was sliding down a well of a place which seemed scores of feet deep and just large enough in diameter to permit the passage of his body. It was the old trick of lower New York, which had been worked thousands of times, and will be worked as many times more.
Nick, who had been up against the trapdoor game before, would naturally have been more careful in that treacherous establishment only for the fact that he believed his disguise perfect, and Hartley rather above the murder of inquisitive men whom he had had no occasion to suspect of greater interference with his plans than the opening of a door for the purpose of listening to a forbidden conversation.
As Nick dropped into the dark tunnel, he heard a trapdoor close above his head, and at the same instant his right heel caught in what seemed to be little more than a horizontal crevice in the wall of the place. At the moment of falling he had crowded his feet out to the sides and his hands to the front, in hope of finding some break to check his fall.
Finding that his heel was slipping from the place where it rested, Nick drew out his knife, which opened as he removed it from his pocket, the blade being controlled by a spring at the back, and drove it into the wall to his left. Supported by this and by the foothold on the right, the detective began an investigation of the place.
He could have used his lantern readily enough, as the right hand was free, but he was afraid of watching eyes, so he groped about in the darkness, hoping to find an outlet about where his heel had struck.
He understood the trap games of New York well enough to know that the shaft communicated with more than one basement of the building, which was an old one and probably full of devices for the destruction of unwelcome guests. If he could come upon a door connecting with the floor directly underneath the store, the trick of the diamond merchant might, after all, be turned to good advantage.
A careful examination of the wall on the right convinced the detective that the door to the first basement was where his foot had struck; that, in fact, his heel rested on a bit of flooring under the crack of the door.
“Now,” he thought, “I wonder which way this door opens? If they throw people down here, it opens into the room; if they back people up against the wall and let them fall in, it opens into the shaft! Ah! Here it is.”