Directly in front of the gramophone,

where Paul had been standing a mo- ment before, a square section of the iron floor swung silently downward, disclosing a dark hole. A few seconds later, as the music ended, the iron plate rose again, but before it could close Paul had sprung forward and thrust it downward again with a stout stick, which he wedged against the next iron waste time." "I saw him about an hour before the plate in such a manner as to prevent the swinging plate: from closing again. incident with Stella-Miss Carfax," re- plied Martin readily. "The ladder, Colonel, please," he "Can you remember what took place between you?" "Can you remember what took place said. "I think we are going to find dangerous professional rival, for I have Roland Vayne." sage, but if I am right, we ought not to delay. If I am wrong-but that can wait. First, I want to ask Mr. Martin some questions." He turned to the young man. "When did you last see Vayne?" he asked. "I know you have told us that already, but I want to arrive at a cer- tain point, so forgive me if I seem to "Easily, for it was only a few words. He told me he had got of a new gramophone record-that is, one I had not already got, and would put it in my room for me. I thanked him and said I would try it when I returned. I was going to make an inspection of the works." "That was a lengthy job?" "About two hours, roughly." "He was friendly to you?" "Of course; we were on excellent terms." "Now, another point: where did you get that large vase that stands on the pedestal over there?" "Vayne gave it to me. He found, it in the ruins. He was very fond of pottering about in the bowels of the earth-there are huge old cellars here, you know, some of which we use for storing dangerous chemicals. I am rather fond of china, and he laughingly told me to add it to my collection, thinking it was rubbish. But, oddly enough, he happened to describe the thing to some friend who is an expert, and the friend told him it was probably a rather good piece of antique stuff. Of course, I asked him to take it back when he told me, but he refused, and we had the pedestal made by one of the carpenters here, so that it would not be within reach of the cleaners, and get broken accidentally." Paul Pry's eyes gleamed. "Now, gentlemen," he said, "I am going to test a theory. If it is correct, we shall solve the mystery of Roland Vayne's disappearance. Please stay where you-" Crossing the room, he approached the gramophone, adjusted the needle and started the clockwork. In a moment the strains of that beautiful selection from Puccini's Madam Butterfly, "One Fine Day," flooded the room with ex- quisite melody. The audience waited eagerly for the next step in this strange drama. As the last notes rang out three of them gave a cry of surprise. W T-2 THE rope-ladder, some fifty feet HE rope-ladder, some fifty feet long, was lowered into the opening, the top being secured by a strong iron. bar, and Paul, taking the torch in his hand, descended slowly. In a few seconds his voice was heard, calling the others to descend. One by one, they entered the square hole and climbed down some thirty rungs of the ladder. They found themselves in a stone- floored cellar, from which a passage led away into the darkness. Near the foot of the ladder stood Paul Pry, beside a shapeless object. As he turned in its direction, the light of the torch which he had held upward to guide their de- scent, the three men saw a huddled body lying on the stones. It was the body of Roland Vayne. There, in that silent cell, in the sol- emn presence of Death, Paul Pry told, in words that were the more moving for their modest simplicity, how he had re- constructed the tragedy in which the young electrician had played so terrible. a part. "When you left me in Vayne's room," he said, "I had already formed a shadowy theory. It is now impossible to say whether I am right or wrong in all my conclusions, but the body beside which we are standing is the final piece of evidence which seems to support what must be a partly speculative line of deduction. I looked through Vayne's papers, and was not surprised to find a plan of the old priory on which, as I had already learned, these works were built up. "I knew that Vayne had been an un- successful suitor for Miss Carfax's hand; that Martin had won the prize that Vayne had not been able to secure; and that Vayne was aware of the fact. I knew, also, that Vayne was a skilled electrician, had a sound knowledge of mechanics, and had access to any part: of the works when he chose. "Colonel Fairbody will tell you that many crimes which seem bizarre are not in reality in the least extraordi- 49 nary; it is not that local circumstances combine to assist the criminal, but the criminal who naturally makes use of local circumstances to assist him in the commission of his crime. "So in this case. I fear there is not much doubt that Vayne attempted to commit a crime, but in the end Provi- dence frustrated his efforts. "Vayne was confronted with two problems: first, to get rid of a man who stood in the way of his love and who, it is not unlikely, he considered a reason to suspect that he himself had ambitions apart from his immediate work, and was deeply engaged in study- ing chemistry." "That is so," murmured Mr. Carfax. Paul bowed. tinued, "was to get rid of John Martin "Vayne's second problem," he con- in such a way that no suspicion would rest on himself. His plan was certainly an ingenious one, but some whimsical streak in the man made him elaborate it so curiously that its very ingenuity made me suspect the truth. "This is not a fitting time or place to detail at length the steps I took: I prefer, rather, to mention only such points as are material to the story. Vayne was aware, as most people are, that certain articles vibrate in varying degrees in sympathy with certain notes of music. He obtained, probably after a careful search, the large vase which stands in Martin's room, and which he had found to vibrate very considerably in response to the note of B flat. "When the vase had been installed for a sufficient time to be half forgot- ten, he attached to it two tiny wires so arranged as to form a make-and-break contact, if I describe it correctly, on the vibration of the vase. That vibration was considerably more than the mere thousandth part of an inch which is actually sufficient to make an electrical connection. These wires led through the wooden pedestal and through the floor. Now, we have heard that Vayne was very found of exploring the cellars of this place, and had pretended to find the vase in one of them. I hope to show you that in his explorations he discov. ered that the whole of this building has been erected directly over a long exca- vation which communicated by a nar- row passage with cellars quite a long way off. The scheme now becomes clear: Vayne during Martin's absence, easily removed a plate from the iron floor in Martin's room, immediately in front of the gramophone--the spot at which a person would naturally stand while ad-