his hand?"

"You must get me that flask, or some of its contents," I directed.
"But tell me, how does he produce the appearance of death?"

"I cannot tell you," she replied. "I do not know. It is something in
the wine. In another hour Aziz will be again as you saw him. But
see." And, opening a little ebony box, she produced a phial half
filled with the amber liquid.

"Good!" I said, and slipped it into my pocket. "When will be the best
time to seize Fu-Manchu and to restore your brother?"

"I will let you know," she whispered, and, opening the door, pushed me
hurriedly from the room. "He is going away to-night to the north; but
you must not come to-night. Quick! Quick! Along the passage. He may
call me at any moment."

So, with the phial in my pocket containing a potent preparation unknown
to Western science, and with a last long look into the eyes of
Karamaneh, I passed out into the narrow alley, out from the fragrant
perfumes of that mystery house into the place of Thames-side stenches.

CHAPTER XXII

"WE must arrange for the house to be raided without delay," said Smith.
"This time we are sure of our ally--"

"But we must keep our promise to her," I interrupted.

"You can look after that, Petrie," my friend said. "I will devote the
whole of my attention to Dr. Fu-Manchu!" he added grimly.

Up and down the room he paced, gripping the blackened briar between his
teeth, so that the muscles stood out squarely upon his lean jaws. The
bronze which spoke of the Burmese sun enhanced the brightness of his
gray eyes.

"What have I all along maintained?" he jerked, looking back at me
across his shoulder--"that, although Karamaneh was one of the strongest
weapons in the Doctor's armory, she was one which some day would be
turned against him. That day has dawned."

"We must await word from her."

"Quite so."

He knocked out his pipe on the grate. Then:

"Have you any idea of the nature of the fluid in the phial?"

"Not the slightest. And I have none to spare for analytical purposes."

Nayland Smith began stuffing mixture into the hot pipe-bowl, and
dropping an almost equal quantity on the floor.

"I cannot rest, Petrie," he said. "I am itching to get to work. Yet,
a false move, and--" He lighted his pipe, and stood staring from the
window.

"I shall, of course, take a needle-syringe with me," I explained.

Smith made no reply.

"If I but knew the composition of the drug which pro