I managed to get up at last, and walk round to the street, and there I saw the name ‘Dr. Black’ on the post by the front gate. As fate or my luck would have it, the door opened and a man came down the steps as I passed by. I had no doubt it was the doctor himself. He was of a type rather common in London; long and thin, with a pasty face and a dull black moustache. He gave me a look as we passed each other on the pavement, and though it was merely the casual glance which one foot-passenger bestows on another, I felt convinced in my mind that here was an ugly customer to deal with. As you may imagine, I went my way a good deal puzzled and horrified too by what I had seen; for I had paid another visit to the ‘General Gordon,’ and had got together a good deal of the common gossip of the place about the Blacks. I didn’t mention the fact that I had seen a woman’s face in the window; but I heard that Mrs. Black had been much admired for her beautiful golden hair, and round what had struck me with such a nameless terror, there was a mist of flowing yellow hair, as it were an aureole of glory round the visage of a satyr. The whole thing bothered me in an indescribable manner; and when I got home I tried my best to think of the impression I had received as an illusion, but it was no use. I knew very well I had seen what I have tried to describe to you, and I was morally certain that I had seen Mrs. Black. And then there was the gossip of the place, the suspicion of foul play, which I knew to be false, and my own conviction that there was some deadly mischief or other going on in that bright red house at the corner of Devon Road: how to construct a theory of a reasonable kind out of these two elements. In short, I found myself in a world of mystery; I puzzled my head over it and filled up my leisure moments by gathering together odd threads of speculation, but I never moved a step towards any real solution, and as the summer days went on the matter seemed to grow misty and indistinct, shadowing some vague terror, like a nightmare of last month. I suppose it would before long have faded into the background of my brain—I should not have forgotten it, for such a thing could never be forgotten—but one morning as I was looking over the paper my eye was caught by a heading over some two dozen lines of small type. The words I had seen were simply, ‘The Harlesden Case,’ and I knew what I was going to read. Mrs. Black was dead. Black had called in another medical man to certify as to cause of death, and something or other had aroused the strange doctor’s suspicions and there had been an inquest and post-mortem. And the result? That, I will confess, did astonish me considerably; it was the triumph of the unexpected. The two doctors who made the autopsy were obliged to confess that they could not discover the faintest trace of any kind of foul play; their most exquisite tests and reagents failed to detect the presence of poison in the most infinitesimal quantity. Death, they found, had been caused by a somewhat obscure and scientifically interesting form of brain disease. The tissue of the brain and the molecules of the grey matter had undergone a most extraordinary series of changes; and the younger of the two doctors, who has some reputation, I believe, as a specialist in brain trouble, made some remarks in giving his evidence which struck me deeply at the time, though I did not then grasp their full significance. He said: ‘At the commencement of the examination I was astonished to find appearances of a character entirely new to me, notwithstanding my somewhat large experience. I need not specify these appearances at present, it will be sufficient for me to state that as I proceeded in my task I could scarcely believe that the brain before me was that of a human being at all.’ There was some surprise at this statement, as you may imagine, and the coroner asked the doctor if he meant to say that the brain resembled that of an animal. ‘No,’ he replied, ‘I should not put it in that way. Some of the appearances I noticed seemed to point in that direction, but others, and these were the more surprising, indicated a nervous organization of a wholly different character from that either of man or the lower animals.’ It was a curious thing to say, but of course the jury brought in a verdict of death from natural causes, and, so far as the public was concerned, the case came to an end. But after I had read what the doctor said I made up my mind that I should like to know a good deal more, and I set to work on what seemed likely to prove an interesting investigation. I had really a good deal of trouble, but I was successful in a measure. Though why—my dear fellow, I had no notion at the time.