“I know your immense experience, sir,” said he. “This is quite unofficial, of course, and need go no farther. But I am fairly up against it in this McPherson case. The question is, shall I make an arrest, or shall I not?”

“Meaning Mr. Ian Murdoch?”

“Yes, sir. There is really no one else when you come to think of it. That’s the advantage of this solitude. We narrow it down to a very small compass. If he did not do it, then who did?”

“What have you against him?”

He had gleaned along the same furrows as I had. There was Murdoch’s character and the mystery which seemed to hang round the man. His furious bursts of temper, as shown in the incident of the dog. The fact that he had quarrelled with McPherson in the past, and that there was some reason to think that he might have resented his attentions to Miss Bellamy. He had all my points, but no fresh ones, save that Murdoch seemed to be making every preparation for departure.

“What would my position be if I let him slip away with all this evidence against him?” The burly, phlegmatic man was sorely troubled in his mind.

“Consider,” I said, “all the essential gaps in your case. On the morning of the crime he can surely prove an alibi. He had been with his scholars till the last moment, and within a few minutes of McPherson’s appearance he came upon us from behind. Then bear in mind the absolute impossibility that he could single-handed have inflicted this outrage upon a man quite as strong as himself. Finally, there is this question of the instrument with which these injuries were inflicted.”

“What could it be but a scourge or flexible whip of some sort?”

“Have you examined the marks?” I asked.

“I have seen them. So has the doctor.”

“But I have examined them very carefully with a lens. They have peculiarities.”

“What are they, Mr. Holmes?”

I stepped to my bureau and brought out an enlarged photograph. “This is my method in such cases,” I explained.

“You certainly do things thoroughly, Mr. Holmes.”

“I should hardly be what I am if I did not. Now let us consider this weal which extends round the right shoulder. Do you observe nothing remarkable?”

“I can’t say I do.”

“Surely it is evident that it is unequal in its intensity. There is a dot of extravasated blood here, and another there. There are similar indications in this other weal down here. What can that mean?”

“I have no idea. Have you?”

“Perhaps I have. Perhaps I haven’t. I may be able to say more soon. Anything which will define what made that mark will bring us a long way towards the criminal.”

“It is, of course, an absurd idea,” said the policeman, “but if a red-hot net of wire had been laid across the back, then these better marked points would represent where the meshes crossed each other.”

“A most ingenious comparison. Or shall we say a very stiff cat-o’-nine-tails with small hard knots upon it?”

“By Jove, Mr. Holmes, I think you have hit it.”

“Or there may be some very different cause, Mr. Bardle. But your case is far too weak for an arrest. Besides, we have those last words - the ‘Lion’s Mane.’ ”

“I have wondered whether Ian- -”

“Yes, I have considered that. If the second word had borne any resemblance to Murdoch - but it did not. He gave it almost in a shriek. I am sure that it was ‘Mane.’ ”

“Have you no alternative, Mr. Holmes?”

“Perhaps I have. But I do not care to discuss it until there is something more solid to discuss.”

“And when will that be?”

“In an hour - possibly less.”

The inspector rubbed his chin and looked at me with dubious eyes.

“I wish I could see what was in your mind, Mr. Holmes. Perhaps it’s those fishing-boats.”