osted here because of the secret panel somewhere in
this wall. You escaped through it before--do you remember?"

"Of course I remember. And if I'd had merely a fraction of your luck
then, my present situation would be quite different."

"Perhaps," said the Hawk. "This panel is now the unknown quantity so
far as I'm concerned, and I don't like unknown quantities; so I am
asking you to show me where it is and how it works. That's my favor.
Of course you can refuse to reveal it, but that will not delay me very
long. The method of compulsion I mentioned...."

Dr. Ku-Sui appeared to reflect a moment, but his decision was not
tardy in coming. He smiled.

"You terrify me, Captain, with your ominous hints about compulsion. I
suppose I'd better be reasonable and show it to you. Really, though,
your concern over the panel is rather wasted, inasmuch as it conceals
nothing more than a small escape passage leading out of this building.
Nothing important at all."

But his words, Carse somehow felt, were a screen; something else lay
beneath them. He watched the tall figure with its always present odor
of tsin-tsin blossoms move forward in a few indecisive steps, then
back again, considering. The smile and the easy words were a
camouflage, surely--but for what?

"Nothing important at all." Dr. Ku Sui repeated pleasantly. "Come. I
will show you. Friday--if I may so address you--over on that
switchboard you will find a small lever-control. It is the one with a
Chinese character above it. Will you be so kind as to throw it?"

The Negro glanced inquiringly at his master. Grimly Carse nodded.

An enigmatic light glimmered in the Eurasian's green eyes as they
watched the Negro go to the switchboard and put thumb and forefinger
on the control.

"Only a small escape passage," he said deprecatingly as the Hawk
crouched, gun ready, his eyes on the suspected place in the wall.

Friday threw the switch.

Immediately there sounded a short, sharp explosion. And acrid smoke
billowed out from under the case of coordinated brains!

* * * * *

Carse sprang to Ku Sui, gripped one arm and cried harshly:

"What have you done?"

"Not I, Captain--your obedient servant, the Black. Please, your
fingers--" He removed them from his arm; and then, smiling, he said:

"I am afraid that all your assurance, your threats, are now but so
much wasted breath."

"You mean--?"

"Surely, Captain," said Ku Sui, "you must