Fantastic as had been the thoughts that during that fraction of time had whirled through my brain, the little gold circlet lying in my palm seemed to propound questions more fantastic still. How in the name of all that was inexplicable had Mrs. Cunningham's engagement-ring come to be there? Each momentary explanation at which I grasped seemed more lunatic than the rest. Had she simply lost it, sought for it and been unable to find it? Had it rolled of itself into that little five-eighths hole? Absurd, since even if by a miraculous chance it had rolled exactly there I had had to take a screwdriver to prise it out. Had she put it there, and for what reason? Ridiculous again, since ladies on the eve of their weddings do not use their rings for the jeweling of holes in one-inch floorboards. Yet if she had not put it there, what idiot had, and why? And what was the hole itself?

Again I was down on my hands and knees, examining the hole. Round—as perfectly round as if it had been drilled with a brace and bit—but not recent. It might at one time have given passage to a gas-pipe, a wire, a cord; it might have been a knot-hole. I peered down it. Nothing but blackness. I explored it again with my finger, and learned nothing new. Just an old hole, now scraped and jagged a little by the screwdriver.

Suddenly I rose, left the studio, and strode through the annexe. Rooke might have had his scruples about prying into the nooks and corners of another man's house, but I assure you I now had none. I was bound for the cellar. If others could go down there so could I. Rooke had said that Philip had left the key in the door. "Right you are, Philip," I muttered to myself. "If Rooke won't I will. Glenfield says you're pulling out, but so am not I. I'm for Hubbard and the optophone theory now. I've an hour or two to spare, and your cellar's going to be examined as it hasn't been yet. Here goes."

But I had all the moral guilt of my intention to abuse his roof-tree with none of the advantages. The door that led to the cellar was once more locked and the key had gone.

Slowly I went back to the studio and the frayed tapestry chair. I wanted to think quietly and at length. Now I pride myself on being rather a methodical sort of thinker when I really give my mind to a thing, and I was resolved to get to the bottom of this if I could. That almost insultingly grotesque discovery of the ring had put me on my mettle. One thing seemed clear, if anything in the whole business was clear: for whatever reason, Mrs. Cunningham had not shared Monty's delicacy about peering and pottering. Of this there seemed to be several indications. Again and again she had insisted that there was something uncanny about the place; she had had an access of hysteria and had had to be brought up from the cellar; and rather than live there she had broken off her engagement. But she had not done this last immediately. Days, if not a week or two—I did not know how long—had elapsed. I was now convinced that during that interval she had made some kind of a discovery. The ring was evidence enough of that. And she had had an advantage in her investigations that I had not: she had had access to the cellar. Then, her discovery made, apparently she had cleared out.

So much for Mrs. Cunningham. Now for the apparatus, all I knew of which was the ring in the knot-hole.

Deliberately I began to reconstruct the events of the morning of the accident from the moment when Esdaile had returned from his unexplained half hour in the cellar. I put pressure on my memory so that not a single detail should escape me. And I experienced a little thrill when, by dint of concentrated thought, I evoked Esdaile's image again at the moment when Hubbard and I had followed him into this very studio. He had been standing with bowed head, poking with his foot at fragments of broken glass and—yes—at the rug on the floor. I could see his foot again, pushing at that very mat over which I had stumbled. The mat had covered the hole then as it covered it now. Esdaile, to all appearances lost in abstraction, had—I began to feel it in my bones—been intently engaged in covering up that hole.

Then, having covered up the hole, what had he done next? Instantly I saw another vivid picture. I saw again those gray moving shapes on the roof, saw Esdaile suddenly stride to the blind-cords, saw the movement with which he had bidden me do the same, and the little bright gold rhomboids of light in the rafters as the deep blue blinds had been shut.

And half an hour later he had sharply forbidden Rooke to touch the blind-cords and had petulantly refused him the key of the cellar.

I felt excitement growing on me. My whole body began to glow with it. I felt myself getting nearer—nearer——

Hubbard was both right and wrong——

He was wrong in his insistence on what Esdaile must have heard——

But he was right about the apparatus——

Esdaile had not heard—he had seen—and there was no more mystery about it all than there is in putting your eye to a keyhole.