bove the shop of J. Salaman where I
knew Fu-Manchu to be. But for some reason the latter window had been
closed or almost closed, and as I stood there this reason became
apparent to me.

The sound of running footsteps came from the direction of New Oxford
Street. I turned--to see two policemen bearing down upon me!

This was a time for quick decisions and prompt action. I weighed all
the circumstances in the balance, and made the last vital choice of
the night; I turned and ran toward the British Museum as though the
worst of Fu-Manchu's creatures, and not my allies the police, were at
my heels!

No one else was in sight, but, as I whirled into the Square, the red
lamp of a slowly retreating taxi became visible some hundred yards to
the left. My leg was paining me greatly, but the nature of the wound
did not interfere with my progress; therefore I continued my headlong
career, and ere the police had reached the end of Museum Street I had
my hand upon the door handle of the cab--for, the Fates being
persistently kind to me, the vehicle was for hire.

"Dr. Cleeve's, Harley Street!" I shouted at the man. "Drive like hell!
It's an urgent case."

I leapt into the cab.

Within five seconds from the time that I slammed the door and dropped
back panting upon the cushions, we were speeding westward toward the
house of the famous pathologist, thereby throwing the police
hopelessly off the track.

Faintly to my ears came the purr of a police whistle. The taxi-man
evidently did not hear the significant sound. Merciful Providence had
rung down the curtain; for to-night my role in the yellow drama was
finished.

CHAPTER XXI

CRAGMIRE TOWER

Less than two hours later, Inspector Weymouth and a party from New
Scotland Yard raided the house in Museum Street. They found the stock
of J. Salaman practically intact, and, in the strangely appointed
rooms above, every evidence of a hasty outgoing. But of the
instruments, drugs and other laboratory paraphernalia not one item
remained. I would gladly have given my income for a year, to have
gained possession of the books, alone; for beyond all shadow of doubt,
I knew them to contain formulae calculated to revolutionize the science
of medicine.

Exhausted, physically and mentally, and with my mind a
whispering-gallery of conjectures (it were needless for me to mention
_whom_ respecting), I turned in, gratefully, having patched up the
slight wound in my calf.

I seemed s