"Not a trace, Knox," he murmured; "not a trace. Let us try again."

He moved along to the yew adjoining that which he had already inspected, but presently shook his head and pa.s.sed to the next. Then:

"Ah!" he cried. "Come here, Knox!"

I joined him where he was kneeling, staring at what I took to be a large nail, or bolt, protruding from the bark of the tree.

"You see!" he exclaimed, "you see!"

I stooped, in order to examine the thing more closely, and as I did so, I realized what it was. It was the bullet which had killed Colonel Menendez!

Harley stood upright, his face slightly flushed and his eyes very bright.

"We shall not attempt to remove it, Knox," he said. "The depth of penetration may have a tale to tell. The wood of the yew tree is one of the toughest British varieties."

"But, Harley," I said, blankly, as we descended to the path, "this is merely another point for the prosecution of Camber. Unless"-I turned to him in sudden excitement, "the bullet was of different-"

"No, no," he murmured, "nothing so easy as that, Knox. The bullet was fired from a Lee-Enfield beyond doubt."

I stared at him uncomprehendingly.

"Then I am utterly out of my depth, Harley. It, appears to me that the case against Camber is finally and fatally complete. Only the motive remains to be discovered, and I flatter myself that I have already detected this."

"I am certainly inclined to think," admitted Harley, "that there is a good deal in your theory."

"Then, Harley," I said in bewilderment, "you do believe that Camber committed the murder?"

"On the contrary," he replied, "I am certain that he did not."

I stood quite still.

"You are certain?" I began.

"I told you that the test of my theory, Knox, was to be looked for in the seventh yew from the northeast corner of the Tudor garden, did I not?"

"You did. And it is there. A bullet fired from a Lee-Enfield rifle; beyond any possible shadow of doubt the bullet which killed Colonel Menendez."

"Beyond any possible shadow of doubt, as you say, Knox, the bullet which killed Colonel Menendez."

"Therefore Camber is guilty?"

"On the contrary, therefore Camber is innocent!"

"What!"

"You are persistently overlooking one little point, Knox," said Harley, mounting the steps on to the gravel path. "I spoke of the seventh yew tree from the northeast corner of the garden."

"Well?"

"Well, my dear fellow, surely you observed that the bullet was embedded in the ninth?"

I was still groping for the significance of this point when, re- crossing the hall, we entered the library again, to find Inspector Aylesbury posed squarely before the mantelpiece stating his case to Wess.e.x.

"You see," he was saying, in his most oratorical manner, as we entered, "every little detail fits perfectly into place. For instance, I find that a woman, called Mrs. Powis, who for the past two years had acted as housekeeper at the Guest House and never taken a holiday, was sent away recently to her married daughter in London. See what that means? Her room is at the back of the house, and her evidence would have been fatal. Ah Tsong, of course, is a liar. I made up my mind about that the moment I clapped eyes on him. Mrs. Camber is the only innocent party. She was asleep in the front of the house when the shot was fired, and I believe her when she says that she cannot swear to the matter of distance."

"A very interesting case, Inspector," said Wess.e.x, glancing at Harley. "I have not examined the body yet, but I understand that it was a clean wound through the head."

"The bullet entered at the juncture of the nasal and frontal bones," explained Harley, rapidly, "and it came out between the base of the occipital and first cervical. Without going into unpleasant surgical details, the wound was a perfectly straight one. There was no ricochet."

"I understand that a regulation rifle was used?"

"Yes," said Inspector Aylesbury; "we have it."

"And at what range did you say, Inspector?"

"Roughly, a hundred yards."

"Possibly less," murmured Harley.

"Hundred yards or less," said Wess.e.x, musingly; "and the obstruction met with in the case of a man shot in that way would be-" He looked towards Paul Harley.

"Less than if the bullet had struck the skull higher up," was the reply. "It pa.s.sed clean through."

"Therefore," continued Wess.e.x, "I am waiting to hear, Inspector, where you found the bullet lodged?"

"Eh?" said the Inspector, and he slowly turned his prominent eyes in Harley's direction. "Oh, I see. That's why you wanted to examine the Tudor garden, is it?"

"Exactly," replied Harley.

The face of Inspector Aylesbury grew very red.

"I had deferred looking for the bullet," he explained, "as the case was already as clear as daylight. Probably Mr. Harley has discovered it."

"I have," said Harley, shortly.

"Is it the regulation bullet?" asked Wess.e.x.

"It is. I found it embedded in one of the yew trees."

"There you are!" exclaimed Aylesbury. "There isn't the ghost of a doubt."

Wess.e.x looked at Harley in undisguised perplexity.

"I must say, Mr. Harley," he admitted, "that I have never met with a clearer case."

"Neither have I," agreed Harley, cheerfully. "I am going to ask Inspector Aylesbury to return here after nightfall. There is a little experiment which I should like to make, and which would definitely establish my case."

"Your case?" said Aylesbury.

"My case, yes."

"You are not going to tell me that you still persist in believing Camber to be innocent?"