"What happened was this. Two days ago I received the letter which I now read to you. Neither address nor date is attached to it.

"'A Russian nobleman who is now resident in England,' it runs, 'would be glad to avail himself of the professional assistance of Dr. Percy Trevelyan. He has been for some years a victim to cataleptic attacks, on which, as is well known, Dr. Trevelyan is an authority. He proposes to call at about quarter past six tomorrow evening, if Dr. Trevelyan will make it convenient to be at home.'

"This letter interest me deeply, because the chief difficulty in the study of catalepsy is the rareness of the disease. You may believe, than, that I was in my consulting-room when, at the appointed hour, the page showed in the patient. He was an elderly man, thin, demure, and commonplace—by no means the conception one forms of a Russian nobleman. I was much more struck by the appearance of his companion. This was a tall young man, surprisingly handsome, with a dark, fierce face, and the limbs and chest of a Hercules. He had his hand under the other's arm as they entered, and helped him to a chair with a tenderness which one would hardly have expected from his appearance.

"'You will excuse my coming in, doctor,' said he to me, speaking English with a slight lisp. 'This is my father, and his health is a matter of the most overwhelming importance to me.'

"I was touched by this filial anxiety. 'You would, perhaps, care to remain during the consultation?' said I.

"'Not for the world,' he cried with a gesture of horror. 'It is more painful to me than I can express. If I were to see my father in one of these dreadful seizures I am convinced that I should never survive it. My own nervous system is an exceptionally sensitive one. With your permission, I will remain in the waiting-room while you go into my father's case.'

"To this, of course, I assented, and the young man withdrew. The patient and I then plunged into a discussion of his case, of which I took exhaustive notes. He was not remarkable for intelligence, and his answers were frequently obscure, which I attributed to his limited acquaintance with our language. Suddenly, however, as I sat writing, he ceased to give any answer at all to my inquiries, and on my turning towards him I was shocked to see that he was sitting bolt upright in his chair, staring at me with a perfectly blank and rigid face. He was again in the grip of his mysterious malady.

"My first feeling, as I have just said, was one of pity and horror. My second, I fear, was rather one of professional satisfaction. I made notes of my patient's pulse and temperature, tested the rigidity of his muscles, and examined his reflexes. There was nothing markedly abnormal in any of these conditions, which harmonized with my former experiences. I had obtained good results in such cases by the inhalation of nitrite of amyl, and the present seemed an admirable opportunity of testing its virtues. The bottle was downstairs in my laboratory, so leaving my patient seated in his chair, I ran down to get it. There was some little delay in finding it—five minutes, let us say—and then I returned. Imagine my amazement to find the room empty and the patient gone.

"Of course, my first act was to run into the waiting-room. The son had gone also. The hall door had been closed, but not shut. My page who admits patients is a new boy and by no means quick. He waits downstairs, and runs up to show patients out when I ring the consulting-room bell. He had heard nothing, and the affair remained a complete mystery. Mr. Blessington came in from his walk shortly afterwards, but I did not say anything to him upon the subject, for, to tell the truth, I have got in the way of late of holding as little communication with him as possible.

"Well, I never thought that I should see anything more of the Russian and his son, so you can imagine my amazement when, at the very same hour this evening, they both came marching into my consulting-room, just as they had done before.

"'I feel that I owe you a great many apologies for my abrupt departure yesterday, doctor,' said my patient. "'I confess that I was very much surprised at it,' said I.

"'Well, the fact is,' he remarked, 'that when I recover from these attacks my mind is always very clouded as to all that has gone before. I woke up in a strange room, as it seemed to me, and made my way out into the street in a sort of dazed way when you were absent.'

"'And I,' said the son, 'seeing my father pass the door of the waiting-room, naturally thought that the consultation had come to an end. It was not until we had reached home that I began to realize the true state of affairs.'

"'Well,' said I, laughing, 'there is no harm done except that you puzzled me terribly; so if you, sir, would kindly step into the waiting-room I shall be happy to continue our consultation which was brought to so abrupt an ending.'

"'For half an hour or so I discussed that old gentleman's symptoms with him, and then, having prescribed for him, I saw him go off upon the arm of his son.

"I have told you that Mr. Blessington generally chose this hour of the day for his exercise. He came in shortly afterwards and passed upstairs. An instant later I heard him running down, and he burst into my consulting-room like a man who is mad with panic.

"'Who has been in my room?' he cried. "'No one,' said I.

"'It's a lie! He yelled. 'Come up and look!'

"I passed over the grossness of his language, as he seemed half out of his mind with fear. When I went upstairs with him he pointed to several footprints upon the light carpet.

"'D'you mean to say those are mine?' he cried.

"They were certainly very much larger than any which he could have made, and were evidently quite fresh. It rained hard this afternoon, as you know, and my patients were the only people who called. It must have been the case, then, that the man in the waiting-room had, for some unknown reason, while I was busy with the other, ascended to the room of my resident patient. Nothing has been touched or taken, but there were the footprints to prove that the intrusion was an undoubted fact.

"Mr. Blessington seemed more excited over the matter than I should have thought possible, though of course it was enough to disturb anybody's peace of mind. He actually sat crying in an armchair, and I could hardly get him to speak coherently. It was his suggestion that I should come round to you, and of course I at once saw the propriety of it, for certainly the incident is a very singular one, though he appears to completely overtake its importance. If you would only come back with me in my brougham, you would at least be able to soothe him, though I can hardly hope that you will be able to explain this remarkable occurrence."

Sherlock Holmes had listened to this long narrative with an intentness which showed me that his interest was keenly aroused. His face was as impassive as ever, but his lids had drooped more heavily over his eyes, and his smoke had curled up more thickly from his pipe to emphasize each curious episode in the doctor's tale. As our visitor concluded, Holmes sprang up without a word, handed me my hat, picked his own from the table, and followed Dr. Trevelyan to the door.

Within a quarter of an hour we had been dropped at the door of the physician's residence in Brook Street, one of those somber, flat-faced houses which one associates with a West-End practice. A small page admitted us, and we began at once to ascend the broad, well-carpeted stair. But a singular interruption brought us to a standstill. The light at the top was suddenly whisked out, and from the darkness came a reedy, quivering voice. "I have a pistol," it cried. "I give you my word that I'll fire if you come any nearer."