"How they died. It was by some curious method of sudden arterial
stoppage. Old as they were, some fiendish trick was employed so
skilfully that the result was actual heart failure. There was no
trace of drugs in lungs or blood. On each man's breast, beneath
the sternum bone I found a dull, barely discernible bruise mark,
which I later removed by a simple massage of the spot!"

Shirley closed his eyes, and passed his hand over his own chest
--along the armpits--behind his ears--he seemed to be mentally
enumerating some list of nerve centers. The physician observed
him curiously.

"I have it, doctor! The sen-si-yao!"

"What do you mean?"

"The most powerful and secret of all the death-strokes of the
Japanese art of jiu-jitsu fighting. I paid two thousand dollars
to learn the course from a visiting instructor when I was in
college. It was worth it for this one occasion."

Shirley arose to his feet, and approached the other, touching his
shoulder.

"Stand up, if you please. Let me ask if this was the location of
the mark?"

The physician, interested in this new professional phase, readily
obeyed. One quick movement of Shirley's muscular hand, the thumb
oddly twisted and stiffened, and a sudden jab in the doctor's