ufficiently to enable
Fu-Manchu to enter unobserved."

"Whilst it produced symptoms which rendered him an easy subject for the
Doctor's influence. It is difficult in this case to separate
hallucination from reality, but I think, Mr. West, that Fu-Manchu must
have exercised an hypnotic influence upon your drugged brain. We have
evidence that he dragged from you the secret of the combination."

"God knows we have!" said West. "But who is this Fu-Manchu, and
how--how in the name of wonder did he get into my chambers?"

Smith pulled out his watch. "That," he said rapidly, "I cannot delay
to explain if I'm to intercept the man who has the plans. Come along,
Petrie; we must be at Tilbury within the hour. There is just a bare
chance."

CHAPTER XX

IT was with my mind in a condition of unique perplexity that I hurried
with Nayland Smith into the cab which waited and dashed off through the
streets in which the busy life of London just stirred into being. I
suppose I need not say that I could penetrate no farther into this,
Fu-Manchu's latest plot, than the drugging of Norris West with hashish?
Of his having been so drugged with Indian hemp--that is, converted
temporarily into a maniac--would have been evident to any medical man
who had heard his statement and noted the distressing after-effects
which conclusively pointed to Indian hemp poisoning. Knowing something
of the Chinese doctor's powers, I could understand that he might have
extracted from West the secret of the combination by sheer force of
will whilst the American was under the influence of the drug. But I
could not understand how Fu-Manchu had gained access to locked chambers
on the third story of a building.

"Smith," I said, "those bird tracks on the window-sill--they furnish
the key to a mystery which is puzzling me."

"They do," said Smith, glancing impatiently at his watch. "Consult
your memories of Dr. Fu-Manchu's habits--especially your memories of
his pets."

I reviewed in my mind the creatures gruesome and terrible which
surrounded the Chinaman--the scorpions, the bacteria, the noxious
things which were the weapons wherewith he visited death upon
whomsoever opposed the establishment of a potential Yellow Empire. But
no one of them could account for the imprints upon the dust of West's
window-sill.

"You puzzle me, Smith," I confessed. "There is much in this
extraordinary case that puzzles me. I can think of nothing to account
f