"I am about to tell you, Mr. Holmes, all that actually occurred, for you already know so much that it is clearly to my interest that you should know all. I have already explained the relationship in which I stood to the Tregennis family. For the sake of the sister I was friendly with the brothers. There was a family quarrel about money which estranged this man Mortimer, but it was supposed to be made up, and I afterwards met him as I did the others. He was a sly, subtle, scheming man, and several things arose which gave me a suspicion of him, but I had no cause for any positive quarrel.
"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 even 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.