With all the strength of his mind and memory Coquenil was studying his adversary.  That beard?  Could it be false?  And the swarthy tone of the skin which he noticed now in the improving light, was that natural?  If not natural, then wonderfully imitated.  And the hands, the arms?  He had watched these from the first, noting every movement, particularly the left hand and the left arm, but he had detected nothing significant; the man used his hands like anyone else, he carried a cane in the right hand, lifted his hat with the right hand, offered the envelope with the right hand.  There was nothing to show that he was not a right-handed man.

“I wonder if you have anything against me personally?” inquired M. Paul.

“On the contrary,” declared the other, “we admire you and wish you well.”

“But you threaten my dog?”

“If necessary, yes.”

“And my mother?”

“If necessary.”

The decisive moment had come, not only because Coquenil’s anger was stirred by this cynical avowal, but because just then there shot around the corner from the Avenue Montaigne a large red automobile which crossed the Champs Elysees slowly, past the fountain and the tulip beds, and, turning into the Avenue Gabrielle, stopped under the chestnut trees, its engines throbbing.  Like a flash it came into the detective’s mind that the same automobile had passed them once before some streets back.  Ah, here was the intended way of escape!  On the front seat were two men, strong-looking fellows, accomplices, no doubt.  He must act at once while the wide street was still between them.

“I ask because—­” began M. Paul with his indifferent drawl, then swiftly drawing his whistle, he sounded a danger call that cut the air in sinister alarm.  The stranger sprang away, but Coquenil was on him in a bound, clutching him by the throat and pressing him back with intertwining legs for a sudden fall.  The bearded man saved himself by a quick turn, and with a great heave of his shoulders broke the detective’s grip, then suddenly he attacked, smiting for the neck, not with clenched fist but with the open hand held sideways in the treacherous cleaving blow that the Japanese use when they strike for the carotid.  Coquenil ducked forward, saving himself, but he felt the descending hand hard as stone on his shoulders.

“He struck with his right,” thought M. Paul.

At the same moment he felt his adversary’s hand close on his throat and rejoiced, for he knew the deadly Jitsu reply to this.  Hardening his neck muscles until they covered the delicate parts beneath like bands of steel, the detective seized his enemy’s extended arm in his two hands, one at the wrist, one at the elbow, and as his trained fingers sought the painful pressure points, his two free arms started a resistless torsion movement on the captured arm.  There is no escape from this movement, no enduring its excruciating pain; to a man taken at such a disadvantage one of two things may happen.  He may yield, and in that case he is hurled helpless over his adversary’s shoulder, or he may resist, with the result that the tendons are torn from his lacerated arm and he faints in agony.