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!'