Colin Camber looked very hard at the speaker, and then equally hard at me.

"Was it at behest of Colonel Menendez that you called upon me, Mr.

Knox?"

"It was not," said Harley, tersely; "it was at mine. And he is here now at my request. Come, sir, we are wasting time. At any moment-"

Colin Camber held up his hand, interrupting him.

"By your leave, Mr. Harley," he said, and there was something compelling in voice and gesture, "I must first perform my duty as a gentleman."

He stepped forward in my direction.

"Mr. Knox, I have grossly insulted you. Yet if you knew what had inspired my behaviour I believe you could find it in your heart to forgive me. I do not ask you to do so, however; I accept the humiliation of knowing that I have mortally offended a guest."

He bowed to me formally, and would have returned to his seat, but:

"Pray say no more," I said, standing up and extending my hand. Indeed, so impressive was the man's strange personality that I felt rather as one receiving a royal pardon than as an offended party being offered an apology. "It was a misunderstanding. Let us forget it."

His eyes gleamed, and he seized my hand in a warm grip.

"You are generous, Mr. Knox, you are generous. And now, sir," he inclined his head in Paul Harley's direction, and resumed his seat.

Harley had suffered this odd little interlude in silence but now:

"Mr. Camber," he said, rapidly, "I sent you a message by your Chinese servant to the effect that the police would be here within ten minutes to arrest you."

"You did, sir," replied Colin Camber, drawing toward him a piece of newspaper upon which rested a dwindling mound of s.h.a.g. "This is most disturbing, of course. But since I have not rendered myself amenable to the law, it leaves me moderately unmoved. Upon your second point, Mr. Harley, I shall beg you, to enlarge. You tell me that Don Juan Menendez is dead?"

He had begun to fill his corn-cob as he spoke the words, but from where I sat I could just see his face, so that although his voice was well controlled, the gleam in his eyes was unmistakable.

"He was shot through the head shortly after midnight."

"What?"

Colin Camber dropped the corn-cob and stood up again, the light of a dawning comprehension in his eyes.

"Do you mean that he was murdered?"

"I do."

"Good G.o.d," whispered Camber, "at last I understand."

"That is why we are here, Mr. Camber, and that is why the police will be here at any moment."

Colin Camber stood erect, one hand resting upon the desk.

"So this was the meaning of the shot which we heard in the night," he said, slowly.

Crossing the room, he closed and locked the study door, then, returning, he sat down once more, entirely, master of himself. Frowning slightly he looked from Harley in my direction, and then back again at Harley.

"Gentlemen," he resumed, "I appreciate the urgency of my danger. Preposterous though I know it to be, nevertheless it is perhaps no more than natural that suspicion should fall upon me."

He was evidently thinking rapidly. His manner had grown quite cool, and I could see that he had focussed his keen brain upon the abyss which he perceived to lie in his path.

"Before I commit myself to any statements which might be used as evidence," he said, "doubtless, Mr. Harley, you will inform me of your exact standpoint in this matter. Do you represent the late Colonel Menendez, do you represent the law, or may I regard you as a perfectly impartial enquirer?"

"You may regard me, Mr. Camber, as one to whom nothing but the truth is of the slightest interest. I was requested by the late Colonel Menendez to visit Cray's Folly."

"Professionally?"

"To endeavour to trace the origin of certain occurrences which had led him to believe his life to be in danger."

Harley paused, staring hard at Colin Camber.

"Since I recognize myself to be standing in the position of a suspect," said the latter, "it is perhaps unfair to request you to acquaint me with the nature of these occurrences?"

"The one, sir," replied Paul Harley, "which most intimately concerns yourself is this: Almost exactly a month ago the wing of a bat was nailed to the door of Cray's Folly."

"What?" exclaimed Colin Camber, leaning forward eagerly-"the wing of a bat? What kind of bat?"

"Of a South American Vampire Bat."

The effect of those words was curious. If any doubt respecting Camber's innocence had remained with me at this time I think his expression as he leaned forward across the desk must certainly have removed it. That the man was intellectually unusual, and intensely difficult to understand, must have been apparent to the most superficial observer, but I found it hard to believe that these moods of his were simulated. At the words "A South American Vampire Bat" the enthusiasm of the specialist leapt into his eyes. Personal danger was forgotten. Harley had trenched upon his particular territory, and I knew that if Colin Camber had actually killed Colonel Menendez, then it had been the act of a maniac. No man newly come from so b.l.o.o.d.y a deed could have acted as Camber acted now.

"It is the death-sign of Voodoo!" he exclaimed, excitedly.

Yet again he arose, and crossing to one of the many cabinets which were in the room, he pulled open a drawer and took out a shallow tray.

My friend was watching him intently, and from the expression upon his bronzed face I could deduce the fact that in Colin Camber he had met the supreme puzzle of his career. As Camber stood there, holding up an object which he had taken from the tray, whilst Paul Harley sat staring at him, I thought the scene was one transcending the grotesque. Here was the suspected man triumphantly producing evidence to hang himself.

Between his finger and thumb Camber held the wing of a bat!

CHAPTER XXII

COLIN CAMBER'S SECRET

"I brought this bat wing from Haiti," he explained, replacing it in the tray. "It was found beneath the pillow of a negro missionary who had died mysteriously during the night."

He returned the tray to the drawer, closed the latter, and, standing erect, raised clenched hands above his head.

"With no thought of blasphemy," he said, "but with reverence, I thank G.o.d from the bottom of my heart that Juan Menendez is dead."

He reseated himself, whilst Harley regarded him silently, then:

"'The evil that men do lives after them,'" he murmured. He rested his chin upon his hand. "A bat wing," he continued, musingly, "a bat wing was nailed to Menendez's door." He stared across at Harley. "Am I to believe, sir, that this was the clue which led you to the Guest House?"

Paul Harley nodded.

"It was."