ing the movements of the two detectives with keen interest. "Certainly there was nothing human about the Thing that attacked me, and I imagine that Berjet's death can be laid at the door of the same agency."
Peret flung himself into a chair and lit a cigarette.
"Any way you look at the thing, it seems preposterous," he said reflectively. "The 'invisible monster' theory is too absurd for serious consideration, and the other theories that have been advanced do not stand up in the presence of the facts. However, let us consider. We will assume that Berjet was, as he said, attacked by ten men. Eh! bien! How did they get out of the room? All of the exits are locked on the inside, as you see.
"There is a small transom over that door opening onto the hall, it is true, but it is not large enough for a child to crawl through, much less a man. Dr. Sprague seemed to think that Berjet was asphyxiated. Yet this room, as you yourself observed when we entered it, sergeant, contained not the slightest trace of any kind of gas. As a matter of fact, the room is lighted by electricity. What are we to conclude from these premises? That the poison fumes, assuming that poison fumes were the cause of Berjet's death, were administered by human hands? If so, oblige me, my friend, by telling me how the owner of those hands got out of the room?"
"Well, if the murderers were invisible, and they were, if the testimony of you and Deweese counts for anything," rejoined Strange, "they might have followed Berjet through the window without having been observed by you."
"Invisible murderers!" snorted Peret, with a contemptuous shrug of his shoulders. "You are growing febble-minded, my friend. Didn't Berjet say he saw his murderers?"
"So you say," returned Strange rudely. "But you didn't see Sprague's murderer, although you claim to have been looking at him when he was attacked. Maybe your eyesight is failing you," he added.
Peret glared at the detective sergeant, but said nothing.
"Perhaps Berjet was subject to a hallucination," ventured Strange, after a moment's thought. "He may just have imagined he saw the murderers."
"Perhaps he just imagined he was murdered, too," retorted the Frenchman, and returned to his examination of the room.
At this juncture someone rapped on the door opening into the hall. Strange crossed the room, turned the key in the lock and, opening the door, admitted Central Bureau Detectives Frank and O'Shane.
"Well?" demanded Strange.
"Major Dobson sent us four men from headquarters, and we've searched the house as you ordered," answered O'Shane. "We drew an absolute blank. The house is empty."
"Hasn't Berjet got a family?" inquired Strange.
"The people next door say that Berjet's wife and daughter are spending the winter at Palm Beach."
"Ain't they any servants?"
"All of the servants go home at night except Adolphe, the murdered man's valet."
"Did you find him?"
"No."
"Was the front door, and the rest of the doors and windows in the house, locked?"
"The front door was not only unlocked but slightly ajar. The rest of the house was secured."
"Do you not think it possible that the murderer might have slipped out of the front door while you were watching without being seen by you?"
"Absolutely not." said O'Shane, emphatically. "I didn't take my eye off the front of the house after you entered it until the men the major sent arrived. Mike watched the back of the house with equal care. Nobody
