“It is nonsense, I say!” Thorne cried again. “You seem to forget, Mr Holmes, that it was I who called you in to the case in the first place!”

“No, I have not forgotten that. It was your first mistake. You were confident that your deception would never be uncovered, and considered that it could only add to your appearance of innocence if you feigned impatience with the police and consulted me. But the truth is now known. The bag in which you secreted the clothes, wig and false beard, which you had worn when playing the part of ‘Quinlivan’, is now in the hands of the railway police.”

“You devil!” cried Thorne in a voice suffused with hatred. “You clever, clever devil!” He made a sudden dive for the desk that stood behind him, yanked open a drawer and drew out a heavy-looking pistol.

In half a second Holmes was across the room and had flung himself on the other man. For a moment they wrestled for the gun, then, with a deafening crash, it went off and a shower of glass fell to the floor as the bullet struck a picture on the wall. Lanner and I sprang forward and attempted to bring Thorne down but, with a hoarse cry of effort, he gave up his struggle for the gun, thrust us aside and raced for the door. In an instant, Holmes had a whistle at his lips and had blown a shrill blast. There followed the sound of a great commotion in the street outside, and we hurried to the front door. Upon the pavement before the house, his face contorted with rage, lay Basil Thorne, held securely in the grip of three uniformed policemen.

*   *   *

“As I have had occasion to remark in the past,” said Holmes as we discussed the case over a whisky and soda in his rooms that evening, “all evidence – even, sometimes, that of eye witnesses – is like a crooked signpost on a winding woodland path. The direction in which it is pointing is never entirely clear, and is apt to change as one changes one’s own position.

“The evidence found in Leicester appeared to indicate that Quinlivan had gone on to Hull, or possibly, as Lanner conjectured, Glasgow. But I was not convinced: if a man is cunning enough to present his pursuers with one false scent, might he not as easily present them with two? It struck me as unlikely, under the circumstances, that both the letter and the timetable should have been left behind as they were. It was almost as if he wished his pursuers to know who he was and where he had gone. There was no envelope with the letter, so we could not say where he had been staying when he received it, and no address upon the letter itself, so we were also unable to find the whereabouts of his one supposed connection, the man who signed himself ‘Reverend Arnold’. There seemed something excessively coincidental about this, and I began to feel the presence of a calculating, guiding hand behind it all, attempting to lead us carefully away upon a path of his choosing. At first glance it appeared we had made discoveries, but in truth we had learnt nothing whatever. Underlying this exercise in futility I seemed to dimly perceive a pattern unfolding; but to what end? This was the question that vexed me, Watson. And then I found the hair, and my perspective on the case altered completely.

“It was a white hair, and seemed likely, therefore, to have come from the head of the man we sought. But it was coarse to the touch, and I quickly realized it was not a human hair at all, but that of a horse. Now, it was not impossible that an ordinary horse’s hair might have been carried into the house on someone’s clothing, but the fact that it was the same shade as the hair of the man who had stayed in the room most recently seemed an odd chance. A closer examination with the aid of a lens revealed that one end of it had been neatly cut, almost certainly with a pair of scissors, while the other end had traces of glue adhering to it. I could not doubt then that it had come from a manufactured article, and it required no great leap of imagination to conjecture that the article in question had been a wig, worn by the room’s last occupant.

“But what did this mean? Why should anyone pretend to be Quinlivan? There seemed no point to it. Unless, I thought, as the idea struck me like a bolt of lightning, the same person pretending to be Quinlivan in Leicester had pretended to be Quinlivan all along! That there was, in other words, no such person, and never had been! That would make sense of the false trails he was strewing before us, for it would clearly have been in his interests to make his assumed character as solid and real as possible for a little while. Then, in a trice, he would take off his disguise and ‘Quinlivan’ would vanish utterly from the face of the earth. But if this were true, then all that had happened must have been planned well in advance, for the fictitious Mr Quinlivan had been flourishing for three months or more. There seemed only one conceivable purpose for such an elaborate plan, and that purpose was the deliberate murder of Lady Yelverton.”

Holmes paused and took a sip from the glass at his elbow.

“You see, Watson, how the discovery of a single hair transformed my view of the case? One moment I was helping Lanner to trace a violent eccentric who appeared to have killed Lady Yelverton in hot-blooded anger, the next I saw unfolding before me a carefully constructed, cold-blooded plot to murder a defenceless old lady. But if ‘Quinlivan’ did not really exist, who was it that had played the part so convincingly for the past three months? I at once thought of Thorne, who had never been seen at the same time as ‘Quinlivan’, who would know of his aunt’s susceptibility to charitable callers and who stood to gain substantially from her death. The case seemed clear.

“Our enquiries at the railway station in Leicester quickly established that no one who had been on duty there on Friday morning could remember seeing a man matching Quinlivan’s description. This puzzled the police, who believed he had purchased a ticket there for Hull or Glasgow; but I took it as a further confirmation of my theory: Lady Yelverton’s murderer had removed his disguise and entered the station inconspicuously as himself, probably, I conjectured, to return to London. If this were so, it was possible he had deposited his disguise somewhere safe, to be collected later, when the hue and cry had died down. I gave Thorne’s description to the clerk who had been on duty at the left-luggage office on Friday, and was gratified to learn that a man exactly answering to it had deposited a leather bag there early in the morning.

“When we returned to London, I made discreet enquiries into the state of Thorne’s affairs, and was soon able to learn that he is very heavily in debt and that his creditors are pressing for their money. Yesterday I travelled down to Leicester again with a recent photograph of Thorne cut from one of the society papers. This was recognized by three separate railway officials who had been on duty the previous Friday: the left-luggage clerk, the ticket clerk and a porter who had been on the platform when the Sheffield to London Express had pulled in.

“I then explained the whole matter to the superintendent of the railway police there, and he ordered Thorne’s bag to be opened at once. Inside we found a white wig and a false beard, together with various items of clothing which Quinlivan had been wearing when last seen. My conjectures were thus precisely confirmed. The superintendent naturally wished to announce the discovery at once, but I managed to persuade him that the better course of action was to say nothing until we had the villain in our grasp. He and two of his men brought Thorne’s bag with them when they came up to town this afternoon with the left-luggage clerk, whose testimony provided us with the dramatic denouement that such a case demands. You know my taste in these things, Watson: the dramatic touch, the rapier-thrust of truth. Life without such moments would be flat indeed!”