These indications, of course, could mean only one thing. The shoes had been worn by someone for whom they were too small.

Now it was clear at a glance that Manderson was always thoroughly well shod and careful, perhaps a little vain, of his small and narrow feet. Not one of the other shoes in the collection, as I soon ascertained, bore similar marks; they had not belonged to a man who squeezed himself into tight shoe-leather. Someone who was not Manderson had worn these shoes, and worn them recently; the edges of the tears were quite fresh.

The possibility of someone having worn them since Manderson's death was not worth considering; the body had only been found about twenty-six hours when I was examining the shoes; besides, why should any one wear them? The possibility of someone having borrowed Manderson's shoes and spoiled them for him, while he was alive, seemed about as negligible. With others to choose from he would not have worn these. Besides, the only men in the place were the butler and the two secretaries. But I do not say that I gave those possibilities even as much consideration as they deserved; for my thoughts were running away with me; and I have always found it good policy, in cases of this sort, to let them have their heads. Ever since I had got out of the train at Marlstone early that morning I had been steeped in details of the Manderson affair; the thing had not once been out of my head. Suddenly the moment had come when the dæmon wakes and begins to range.

Let me put it less fancifully. After all, it is a detail of psychology familiar enough to all whose business or inclination brings them in contact with difficult affairs of any sort. Swiftly and spontaneously, when chance or effort puts one in possession of the key-fact in any system of baffling circumstances, one's ideas seem to rush to group themselves anew in relation to that fact, so that they are suddenly rearranged almost before one has consciously grasped the significance of the key-fact itself. In the present instance, my brain had scarcely formulated within itself the thought, 'Somebody who was not Manderson has been wearing those shoes,' when there flew into my mind a flock of ideas, all of the same character and all bearing upon this new notion. It was unheard-of for Manderson to drink much whisky at night. It was very unlike him to be untidily dressed, as the body was when found—the cuffs dragged up inside the sleeves, the shoes unevenly laced; very unlike him not to wash, when he rose, and to put on last night's evening shirt and collar and underclothing; very unlike him to have his watch in the waistcoat pocket that was not lined with leather for its reception. (In my first despatch I mentioned all these points, but neither I nor any one else saw anything significant in them, when examining the body.) It was very strange, in the existing domestic situation, that Manderson should be communicative to his wife about his doings, especially at the time of his going to bed, when he seldom spoke to her at all. It was extraordinary that Manderson should leave his bedroom without his false teeth.

All these thoughts, as I say, came flocking into my mind together, drawn from various parts of my memory of the morning's inquiries and observations. They had all presented themselves, in far less time than it takes to read them as set down here, as I was turning over the shoes, confirming my own certainty on the main point. And yet when I confronted the definite idea that had sprung up suddenly and unsupported before me,—It was not Manderson who was in the house that night—it seemed a stark absurdity at the first formulating. It was certainly Manderson who had dined at the house and gone out with Marlowe in the car. People had seen him at close quarters. But was it he who returned at ten? That question too seemed absurd enough. But I could not set it aside. It seemed to me as if a faint light was beginning to creep over the whole expanse of my mind, as it does over land at dawn, and that presently the sun would be rising. I set myself to think over, one by one, the points that had just occurred to me, so as to make out, if possible, why any man masquerading as Manderson should have done these things that Manderson would not have done.

I had not to cast about very long for the motive a man might have in forcing his feet into Manderson's narrow shoes. The examination of footmarks is very well understood by the police. But not only was the man concerned to leave no footmarks of his own. He was concerned to leave Manderson's, if any; his whole plan, if my guess was right, must have been directed to producing the belief that Manderson was in the place that night. Moreover, his plan did not turn upon leaving footmarks. He meant to leave the shoes themselves, and he did so. The maidservant had found them outside the bedroom door, as Manderson always left his shoes, and had polished them, replacing them on the shoe-shelves later in the morning, after the body had been found.

When I came to consider in this new light the leaving of the false teeth, an explanation of what had seemed the maddest part of the affair broke upon me at once. A dental plate is not inseparable from its owner. If my guess was right, the unknown had brought the denture to the house with him, and left it in the bedroom, with the same object as he had in leaving the shoes; to make it impossible that any one should doubt that Manderson had been in the house and had gone to bed there. This, of course, led me to the inference that Manderson was dead before the false Manderson came to the house; and other things confirmed this.

For instance, the clothing, to which I now turned in my review of the position: if my guess was right, the unknown in Manderson's shoes had certainly had possession of Manderson's trousers, waistcoat and shooting jacket. They were there before my eyes in the bedroom; and Martin had seen the jacket—which nobody could have mistaken—upon the man who sat at the telephone in the library. It was now quite plain (if my guess was right) that this unmistakable garment was a cardinal feature of the unknown's plan. He knew that Martin would take him for Manderson at the first glance.

And there my thinking was interrupted by the realization of a thing that had escaped me before. So strong had been the influence of the unquestioned assumption that it was Manderson who was present that night, that neither I nor, so far as I know, any one else had noted the point. Martin had not seen the man's face; nor had Mrs. Manderson.

Mrs. Manderson (judging by her evidence at the inquest, of which, as I have said, I had a full report made by the Record stenographers in court) had not seen the man at all. She hardly could have done, as I shall show presently. She had merely spoken with him as she lay half asleep, resuming a conversation which she had had with her living husband about an hour before. Martin, I perceived, could only have seen the man's back, as he sat crouching over the telephone; no doubt a characteristic pose was imitated there. And the man had worn his hat, Manderson's broad-brimmed hat! There is too much character in the back of a head and neck. The unknown, in fact, supposing him to have been of about Manderson's build, had had no need for any disguise, apart from the jacket and the hat and his powers of mimicry.