“One day, only a couple of weeks ago, he came down to my cottage and I showed him some of my African curiosities. Among other things I exhibited this powder, and I told him of its strange properties, how it stimulates those brain centres which control the emotion of fear, and how either madness or death is the fate of the unhappy native who is subjected to the ordeal by the priest of his tribe. I told him also how powerless European science would be to detect it. How he took it I cannot say, for I never left the room, but there is no doubt that it was then, while I was opening cabinets and stooping to boxes, that he managed to abstract some of the devil’s-foot root. I well remember how he plied me with questions as to the amount and the time that was needed for its effect, but I little dreamed that he could have a personal reason for asking.

“I thought no more of the matter until the vicar’s telegram reached me at Plymouth. This villain had thought that I would be at sea before the news could reach me, and that I should be lost for years in Africa. But I returned at once. Of course, I could not listen to the details without feeling assured that my poison had been used. I came round to see you on the chance that some other explanation had suggested itself to you. But there could be none. I was convinced that Mortimer Tregennis was the murderer; that for the sake of money, and with the idea, perhaps, that if the other members of his family were all insane he would be the sole guardian of their joint property, he had used the devil’s-foot powder upon them, driven two of them out of their senses, and killed his sister Brenda, the one human being whom I have ever loved or who has ever loved me. There was his crime; what was to be his punishment?

“Should I appeal to the law? Where were my proofs? I knew that the facts were true, but could I help to make a jury of countrymen believe so fantastic a story? I might or I might not. But I could not afford to fail. My soul cried out for revenge. I have said to you once before, Mr. Holmes, that I have spent much of my life outside the law, and that I have come at last to be a law to myself. So it was now. I determined that the fate which he had given to others should be shared by himself. Either that or I would do justice upon him with my own hand. In all England there can be no man who sets less value upon his own life than I do at the present moment.

“Now I have told you all. You have yourself supplied the rest. I did, as you say, after a restless night, set off early from my cottage. I foresaw the difficulty of arousing him, so I gathered some gravel from the pile which you have mentioned, and I used it to throw up to his window. He came down and admitted me through the window of the sitting-room. I laid his offence before him. I told him that I had come both as judge and executioner. The wretch sank into a chair, paralyzed at the sight of my revolver. I lit the lamp, put the powder above it, and stood outside the window, ready to carry out my threat to shoot him should he try to leave the room. In five minutes he died. My God! how he died! But my heart was flint, for he endured nothing which my innocent darling had not felt before him. There is my story, Mr. Holmes. Perhaps, if you loved a woman, you would have done as much yourself. At any rate, I am in your hands. You can take what steps you like. As I have already said, there is no man living who can fear death less than I do.”

Holmes sat for some little time in silence.

“What were your plans?” he asked at last.

“I had intended to bury myself in central Africa. My work there is but half finished.”

“Go and do the other half,” said Holmes. “I, at least, am not prepared to prevent you.”

Dr. Sterndale raised his giant figure, bowed gravely, and walked from the arbour. Holmes lit his pipe and handed me his pouch.