Somehow we extricated ourselves, jeered at by taxi-drivers, who naturally took us for two simple Oriental visitors, and just before that impassable barrier the arm of a London policeman was lowered and the stream moved on a faint breath of perfume became perceptible to me.

The cabs and cars about us were actually beginning to move again, and there was nothing for it but a hasty retreat to the curb.  I could not pause to glance behind, but instinctively I knew that someone—­someone who used that rare, fragrant essence—­ was leaning from the window of the car.

“Andaman—­second!” floated a soft whisper.

We gained the pavement as the pent-up traffic roared upon its way.

Smith had not noticed the perfume worn by the unseen occupant of the car, had not detected the whispered words.  But I had no reason to doubt my senses, and I knew beyond question that Fu-Manchu’s lovely slave, Karamaneh, had been within a yard of us, had recognized us, and had uttered those words for our guidance.

On regaining my rooms, we devoted a whole hour to considering what “Andaman—­second” could possibly mean.

“Hang it all!” cried Smith, “it might mean anything—­ the result of a race, for instance.”

He burst into one of his rare laughs, and began to stuff broadcut mixture into his briar.  I could see that he had no intention of turning in.

“I can think of no one—­no one of note—­in London at present upon whom it is likely that Fu-Manchu would make an attempt,” he said, “except ourselves.”

We began methodically to go through the long list of names which we had compiled and to review our elaborate notes.  When, at last, I turned in, the night had given place to a new day.  But sleep evaded me, and “Andaman—­second” danced like a mocking phantom through my brain.

Then I heard the telephone bell.  I heard Smith speaking.

A minute afterwards he was in my room, his face very grim.

“I knew as well as if I’d seen it with my own eyes that some black business was afoot last night,” he said.  “And it was.  Within pistol-shot of us!  Someone has got at Frank Norris West.  Inspector Weymouth has just been on the ’phone.”

“Norris West!” I cried, “the American aviator—­and inventor—­” “Of the West aero-torpedo—­yes.  He’s been offering it to the English War Office, and they have delayed too long.”

I got out of bed.

“What do you mean?”

“I mean that the potentialities have attracted the attention of Dr. Fu-Manchu!”

Those words operated electrically.  I do not know how long I was in dressing, how long a time elapsed ere the cab for which Smith had ’phoned arrived, how many precious minutes were lost upon the journey; but, in a nervous whirl, these things slipped into the past, like the telegraph poles seen from the window of an express, and, still in that tense state, we came upon the scene of this newest outrage.