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
