We had walked into the library, and, stopping, suddenly, Harley stared me very hard in the face.

"You are bottling something up, Knox," he declared. "Out with it. Has Aylesbury distinguished himself again?"

"No," I replied; "on the contrary. He interviewed Madame de Stamer, and came out with a flea in his ear."

"Good," said Harley, smiling. "A clever woman, and a woman of spirit, Knox."

"You are right," I replied, "and you are also right in supposing that I have a communication to make to you."

"Ah, I thought so. What is it?"

"It is a theory, Harley, which appears to me to cover the facts of the case."

"Indeed?" said he, continuing to stare at me. "And what inspired it?"

"I was staring up at the window of the smoke-room to-day, and I remembered the shadow which you had seen upon the blind."

"Yes?" he cried, eagerly; "and does your theory explain that, too?"

"It does, Harley."

"Then I am all anxiety to hear it."

"Very well, then, I will endeavour to be brief. Do you recollect Miss Beverley's story of the unfamiliar footsteps which pa.s.sed her door on several occasions?"

"Perfectly."

"You recollect that you, yourself, heard someone crossing the hall, and that both of us heard a door close?"

"We did."

"And finally you saw the shadow of a woman upon the blind of the Colonel's private study. Very well. Excluding the preposterous theory of Inspector Aylesbury, there is no woman in Cray's Folly whose footsteps could possibly have been heard in that corridor, and whose shadow could possibly have been seen upon the blind of Colonel Menendez's room."

"I agree," said Harley, quietly. "I have definitely eliminated all the servants from the case. Therefore, proceed, Knox, I am all attention."

"I will do so. There is a door on the south side of the house, close to the tower and opening into the rhododendron shrubbery. This was the door used by Colonel Menendez in his somnambulistic rambles, according to his own account. Now, a.s.suming his statement to have been untrue in one particular, that is, a.s.suming he was not walking in his sleep, but was fully awake-"

"Eh?" exclaimed Harley, his expression undergoing a subtle change. "Do you think his statement was untrue?"

"According to my theory, Harley, his statement was untrue, in this particular, at least. But to proceed: Might he not have employed this door to admit a nocturnal visitor?"

"It is feasible," muttered Harley, watching me closely.

"For the Colonel to descend to this side door when the household was sleeping," I continued, "and to admit a woman secretly to Cray's Folly, would have been a simple matter. Indeed, on the occasions of these visits he might even have unbolted the door himself after Pedro had bolted it, in order to enable her to enter without his descending for the purpose of admitting her."

"By heavens! Knox," said Harley, "I believe you have it!"

His eyes were gleaming excitedly, and I proceeded:

"Hence the footsteps which pa.s.sed Miss Beverley's door, hence the shadow which you saw upon the blind; and the sounds which you detected in the hall were caused, of course, by this woman retiring. It was the door leading into the shrubbery which we heard being closed!"

"Continue," said Harley; "although I can plainly see to what this is leading."

"You can see, Harley?" I cried; "of course you can see! The enmity between Camber and Menendez is understandable at last."

"You mean that Menendez was Mrs. Camber's lover?"

"Don't you agree with me?"

"It is feasible, Knox, dreadfully feasible. But go on."

"My theory also explains Colin Camber's lapse from sobriety. It is legitimate to suppose that his wife, who was a Cuban, had been intimate with Menendez before her meeting with Camber. Perhaps she had broken the tie at the time of her marriage, but this is mere supposition. Then, her old lover, his infatuation by no means abated, leases the property adjoining that of his successful rival."

"Knox!" exclaimed Paul Harley, "this is brilliant. I am all impatience for the denouement."

"It is coming," I said, triumphantly. "Relations are reestablished, clandestinely. Colin Camber learns of these. A pa.s.sionate quarrel ensues, resulting in a long drinking bout designed to drown his sorrows. His love for his wife is so great that he has forgiven her this infidelity. Accordingly, she has promised to see her lover no more. Hers was the figure which you saw outlined upon the blind on the night before the tragedy, Harley! The gestures, which you described as those of despair, furnish evidence to confirm my theory. It was a final meeting!"

"Hm," muttered Harley. "It would be taking big chances, because we have to suppose, Knox, that these visits to Cray's Folly were made whilst her husband was at work in the study. If he had suddenly decided to turn in, all would have been discovered."

"True," I agreed, "but is it impossible?"

"No, not a bit. Women are dreadful gamblers. But continue, Knox."

"Very well. Colonel Menendez has refused to accept his dismissal, and Mrs. Camber had been compelled to promise, without necessarily intending to carry out the promise, that she would see him again on the following night. She failed to come; whereupon he, growing impatient, walked out into the grounds of Cray's Folly to look for her. She may even have intended to come and have been intercepted by her husband. But in any event, the latter, seeing the man who had wronged him, standing out there in the moonlight, found temptation to be too strong. On the whole, I favour the idea that he had intercepted his wife, and s.n.a.t.c.hing up a rifle, had actually gone out into the garden with the intention of shooting Menendez."

"I see," murmured Harley in a low voice. "This hypothesis, Knox, does not embrace the Bat Wing episodes."

"If Menendez has lied upon one point," I returned, "it is permissible to suppose that his entire story was merely a tissue of falsehood."

"I see. But why did he bring me to Cray's Folly?"

"Don't you understand, Harley?" I cried, excitedly. "He really feared for his life, since he knew that Camber had discovered the intrigue."

Paul Harley heaved a long sigh.

"I must congratulate you, Knox," he said, gravely, "upon a really splendid contribution to my case. In several particulars I find myself nearer to the truth. But the definite establishment or shattering of your theory rests upon one thing."

"What's that?" I asked. "You are surely not thinking of the bat wing nailed upon the door?"

"Not at all," he replied. "I am thinking of the seventh yew tree from the northeast corner of the Tudor garden."

CHAPTER XXIX

A LEE-ENFIELD RIFLE

What reply I should have offered to this astonishing remark I cannot say, but at that moment the library door burst open unceremoniously, and outlined against the warmly illuminated hall, where sunlight poured down through the dome, I beheld the figure of Inspector Aylesbury.

"Ah!" he cried, loudly, "so you have come back, Mr. Harley? I thought you had thrown up the case."

"Did you?" said Harley, smilingly. "No, I am still persevering in my ineffectual way."