vant's master. He hears the
woman declare that she has had no admirer but himself, that this unknown
Russian was, and is, nothing to her, that there is no man she loves but
him, and that she cannot live, knowing that he is alive, without his
love. Suppose Chetney believed her, suppose his former infatuation for
her returned, and that in a moment of weakness he forgave her and took
her in his arms. That is the moment the Russian master has feared. It is
to guard against it that he has placed his watchdog over the Princess,
and how do we know but that, when the moment came, the watchdog served
his master, as he saw his duty, and killed them both? What do you
think?' Lyle demanded. 'Would not that explain both murders?'

[Illustration: 15 Entreating Chetney not to leave her]

"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 o