Clearly it was a signal; for, hearing it, Hassan dropped the tube
and glanced toward the open window.

In that instant I sprang upon him!

That I had to deal with a fanatic, a dangerous madman, I knew; that
it was his life or mine, I was fully convinced. I struck out then
and caught him fairly over the heart. He reeled back, and I made
a wild clutch for the damnable tube, horrid, unreasoning fear of
which thus far had held me inert.

I heard the girl scream affrightedly, and I knew, and felt my heart
chill to know, that the tube had been wrenched from my hand! Hassan
of Aleppo, old man that he appeared, had the strength of a tiger. He
recovered himself and hurled me from him so that I came to the floor
crashingly half under my writing-table!

Something he cried back at me, furiously--and like an enraged animal,
his teeth gleaming out from his beard, he darted from the room. The
front door banged loudly.

Shaken and quivering, I got upon my feet. On the threshold, in a
state of pitiable hesitancy, stood the pale, beautiful accomplice
of Earl Dexter. One quick glance she flashed at me, then turned
and ran!

Again the door slammed. I ran to the window, looking out into the
court. The girl came hurrying down the steps, and with never a
backward glance ran on and was lost to view in one of the passages
opening riverward.

Out under the arch, statelily passed a tall figure--and Inspector
Bristol was entering! I saw the detective glance aside as the two
all but met. He stood still, and looked back!

"Bristol!" I cried, and waved my arms frantically.

"Stop him! Stop him! It's Hassan of Aleppo!"

Bristol was not the only one to hear my wild cry--not the only one
to dash back under the arch and out into Fleet Street.

But Hassan of Aleppo was gone!

CHAPTER XXII

THE LIGHT OF EL-MEDINEH

Bristol and I walked slowly in the direction of the entrance of the
British Antiquarian Museum. It was the day following upon the
sensational scene in my chambers.

"There's very little doubt," said Bristol, "that Earl Dexter has
the slipper and that Hassan of Aleppo knows where Dexter is in
hiding. I don't know which of the two is more elusive. Hassan
apparently melted into thin air yesterday; and although The Stetson
Man has never within my experience employed disguises, no one has
set eyes upon him since the night that he vanished from his lodgings
off the Waterloo Road. It's always possible for a