and despite the infinitely greater
knowledge and wider experience of Nayland Smith, what did I know, what
did he know, of the strange organization called the Si-Fan, and of its
most formidable member, Dr. Fu-Manchu?

Where did the dreadful Chinaman hide, with his murderers, his poisons,
and his nameless death agents? What roof in broad England sheltered
Karamaneh, the companion of my dreams, the desire of every waking hour?

I uttered a sigh of despair, when, to my unbounded astonishment, there
came a loud rap upon the window pane!

Leaping up, I crossed to the window, threw it widely open and leant out,
looking down into the court below. It was deserted. In no other window
visible to me was any light to be seen, and no living thing moved in
the shadows beneath. The clamor of Fleet Street's diminishing traffic
came dimly to my ears; the last stroke from St. Paul's quivered through
the night.

What was the meaning of the sound which had disturbed me? Surely I
could not have imagined it? Yet, right, left, above and below, from the
cloisteresque shadows on the east of the court to the blank wall of the
building on the west, no living thing stirred.

Quietly, I reclosed the window, and stood by it for a moment listening.
Nothing occurred, and I returned to the writing-table, puzzled but in
no sense alarmed. I resumed the seemingly interminable record of the
Si-Fan mysteries, and I had just taken up my pen, when ... two loud
raps sounded upon the pane behind me.

In a trice I was at the window, had thrown it open, and was craning
out. Practical joking was not characteristic of Nayland Smith, and I
knew of none other likely to take such a liberty. As before, the court
below proved to be empty....

Some one was softly rapping at the door of the chambers!

I turned swiftly from the open window; and now, came _fear_.
Momentarily, the icy finger of panic touched me, for I thought myself
invested upon all sides. Who could this late caller be, this midnight
visitor who rapped, ghostly, in preference to ringing the bell?

From the table drawer I took out a Browning pistol, slipped it into my
pocket and crossed to the narrow hallway. It was in darkness, but I
depressed the switch, lighting the lamp. Toward the closed door I looked
--as the soft rapping was repeated.

I advanced; then hesitated, and, strung up to a keen pitch of fearful
anticipation, stood there in doubt. The silence remained unbroken for
the space, perhap