“Mr. West’s statement,” I said, “ran closely parallel with portions of Moreau’s book on `Hashish Hallucinations.’  Only Fu-Manchu, I think, would have thought of employing Indian hemp.  I doubt, though, if it was pure Cannabis indica.  At any rate, it acted as an opiate—­”

“And drugged Mr. West,” interrupted Smith, “sufficiently 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 for the marks.”

“Have you thought of Fu-Manchu’s marmoset?” asked Smith.