"'How long ago was it?'

　　"'Oh, not very many minutes.'

　　"'Within the last five?'

　　"'Well, it could not have been more than five.'

　　"'You're only wasting your time, sir, and every minute now is ofimportance,' cried the commissionaire; 'take my word for it that myold woman has nothing to do with it and come down to the other endof the street. Well, if you won't, I will.' And with that he rashedoff in the other direction.

　　"'But I was after him in an instant and caught him by the sleeve."'Where do you live?' said I.

　　"'16 Ivy Lane, Brixton,' he answered. 'But don't let yourself bedrawn away upon a false scent, Mr. Phelps. Come to the other end ofthe street and let us see if we can hear of anything.'

　　"Nothing was to be lost by following his advice. With thepoliceman we both hurried down, but only to find the street full oftraffic, many people coming and going, but all only too eager to getto a place of safety upon so wet a night. There was no lounger whocould tell us who had passed.

　　"Then we returned to the office and searched the stairs and thepassage without result. The corridor which led to the room was laiddown with a kind of creamy linoleum which shows an impression veryeasily. We examined it very carefully, but found no outline of anyfootmark."

　　"Had it been raining all evening?"

　　"Since about seven."

　　"How is it, then, that the woman who came into the room about nineleft no traces with her muddy boots?"

　　"I am glad you raised the point. It occurred to me at the time.The charwomen are in the habit of taking off their boots at thecommissionaire's office, and putting on list slippers.""That is very clear. There were no marks then, though the nightwas a wet one? The chain of events is certainly one of extraordinaryinterest. What did you do next?"

　　"We examined the room also. There is no possibility of a secretdoor, and the windows are quite thirty feet from the ground. Both ofthem were fastened on the inside. The carpet prevents anypossibility of a trapdoor, and the ceiling is of the ordinarywhitewashed kind. I will pledge my life that whoever stole my paperscould only have come through the door."