“Good God!” said young Jarnock again. “Good God! It’s the dagger! The thing’s been stabbed, same as Bellett!”
“Yes,” I replied, and saw him glance swiftly toward the entrance of the Chapel. But I will do him the justice to say that he never budged an inch.
“Come and see how it was done,” I said, and led the way back to the chancel rail. From the wall to the left of the altar I took down a long, curiously ornamented, iron instrument, not unlike a short spear. The sharp end of this I inserted in a hole in the left-hand gatepost of the chancel gateway. I lifted hard, and a section of the post, from the floor upward, bent inward toward the altar, as though hinged at the bottom. Down it went, leaving the remaining part of the post standing. As I bent the movable portion lower there came a quick click and a section of the floor slid to one side, showing a long, shallow cavity, sufficient to enclose the post. I put my weight to the lever and hove the post down into the niche. Immediately there was a sharp clang, as some catch snicked in, and held it against the powerful operating spring.
I went over now to the dummy, and after a few minute’s work managed to wrench the dagger loose out of the armor. I brought the old weapon and placed its hilt in a hole near the top of the post where it fitted loosely, the point upward. After that I went again to the lever and gave another strong heave, and the post descended about a foot, to the bottom of the cavity, catching there with another clang. I withdrew the lever and the narrow strip of floor slid back, covering post and dagger, and looking no different from the surrounding surface.
Then I shut the chancel gate, and we both stood well to one side. I took the spear-like lever, and gave the gate a little push, so that it opened. Instantly there was a loud thud, and something sang through the air, striking the bottom wall of the Chapel. It was the dagger. I showed Jarnock then that the other half of the post had sprung back into place, making the whole post as thick as the one upon the right-hand side of the gate.
“There!” I said, turning to the young man and tapping the divided post. “There’s the ‘invisible’ thing that used the dagger, but who the deuce is the person who sets the trap?” I looked at him keenly as I spoke.
“My father is the only one who has a key,” he said. “So it’s practically impossible for anyone to get in and meddle.”
I looked at him again, but it was obvious that he had not yet reached out to any conclusion.
“See here, Mr. Jarnock,” I said, perhaps rather curter than I should have done, considering what I had to say. “Are you quite sure that Sir Alfred is quite balanced—mentally?”
“He looked at me, half frightenedly and flushing a little. I realized then how badly I put it.
“‘I—I don’t know,’ he replied, after a slight pause and was then silent, except for one or two incoherent half remarks.