“I was only too willing to hear any theory which pointed to any one else as the criminal than Arthur, but Lyle’s explanation was too utterly fantastic. I told him that he certainly showed imagination, but that he could not hang a man for what he imagined he had done.
“‘No,’ Lyle answered, ‘but I can frighten him by telling him what I think he has done, and now when I again question the Russian servant I will make it quite clear to him that I believe he is the murderer. I think that will open his mouth. A man will at least talk to defend himself. Come,’ he said, ‘we must return at once to Scotland Yard and see him. There is nothing more to do here.’
“He arose, and I followed him into the hall, and in another minute we would have been on our way to Scotland Yard. But just as he opened the street door a postman halted at the gate of the garden, and began fumbling with the latch.
“Lyle stopped, with an exclamation of chagrin.
“‘How stupid of me!’ he exclaimed. He turned quickly and pointed to a narrow slit cut in the brass plate of the front door. ‘The house has a private letter-box,’ he said, ‘and I had not thought to look in it! If we had gone out as we came in, by the window, I would never have seen it. The moment I entered the house I should have thought of securing the letters which came this morning. I have been grossly careless.’ He stepped back into the hall and pulled at the lid of the letterbox, which hung on the inside of the door, but it was tightly locked. At the same moment the postman came up the steps holding a letter. Without a word Lyle took it from his hand and began to examine it. It was addressed to the Princess Zichy, and on the back of the envelope was the name of a West End dressmaker.
“‘That is of no use to me,’ Lyle said. He took out his card and showed it to the postman. ‘I am Inspector Lyle from Scotland Yard,’ he said. ‘The people in this house are under arrest. Everything it contains is now in my keeping. Did you deliver any other letters here this morning!’
“The man looked frightened, but answered promptly that he was now upon his third round. He had made one postal delivery at seven that morning and another at eleven.
“‘How many letters did you leave here!’ Lyle asked.
“‘About six altogether,’ the man answered.
“‘Did you put them through the door into the letter-box!’