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, as 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 w