?' he cried. 'It means that some one
has been here ahead of us. Some one has entered this house not three
hours before we came, since eleven o'clock this morning.'

"'It was the Russian servant!' I exclaimed.

"'The Russian servant has been under arrest at Scotland Yard,' Lyle
cried. 'He could not have taken the letters. Lord Arthur has been in his
cot at the hospital. That is his alibi. There is some one else, some one
we do not suspect, and that some one is the murderer. He came back here
either to obtain those letters because he knew they would convict him,
or to remove something he had left here at the time of the murder,
something incriminating,--the weapon, perhaps, or some personal article;
a cigarette-case, a handkerchief with his name upon it, or a pair of
gloves. Whatever it was it must have been damning evidence against him
to have made him take so desperate a chance.'

"'How do we know,' I whispered, 'that he is not hidden here now?'

"'No, I'll swear he is not,' Lyle answered. 'I may have bungled in some
things, but I have searched this house thoroughly. Nevertheless,' he
added, 'we must go over it again, from the cellar to the roof. We have
the real clew now, and we must forget the others and work only it.' As
he spoke he began again to search the drawing-room, turning over even
the books on the tables and the music on the piano. "'Whoever the man
is,' he said over his shoulder, 'we know that he has a key to the front
door and a key to the letter-box. That shows us he is either an inmate
of the house or that he comes here when he wishes. The Russian says
that he was the only servant in the house. Certainly we have found no
evidence to show that any other servant slept here. There could be
but one other person who would possess a key to the house and the
letter-box--and he lives in St. Petersburg. At the time of the murder he
was two thousand miles away.' Lyle interrupted himself suddenly with a
sharp cry and turned upon me with his eyes flashing. 'But was he?' he
cried. 'Was he? How do we know that last night he was not in London, in
this very house when Zichy and Chetney met?'

"He stood staring at me without seeing me, muttering, and arguing with
himself.

"'Don't speak to me,' he cried, as I ventured to interrupt him. 'I can
see it now. It is all plain. It was not the servant, but his master, the
Russian himself, and it was he who came back for the letters! He came
back for them because he knew th