eturning the envelope.

"Then you refuse?"

"I refuse."

"Stubborn fellow! And unbelieving! You doubt our power against you. Come, I
will give you a glimpse of it, just the briefest glimpse. Suppose you try
to arrest me. You have been thinking of it, _now act_. I'm a suspicious
character, I ought to be investigated. Well, do your duty. I might point
out that such an arrest would accomplish absolutely nothing, for you
haven't the slightest evidence against me and can get none, but I waive
that point because I want to show you that, even in so simple an effort
against us as this, _you would inevitably fail_."

The man's impudence was passing all bounds. "You mean that I _cannot_
arrest you?" menaced Coquenil.

"Precisely. I mean that with all your cleverness and with a distinct
advantage in position, here on the Champs Elysees with policemen all about
us, _you cannot arrest me_."

"We'll see about that," answered M. Paul, a grim purpose showing in his
deep-set eyes.

"I say this in no spirit of bravado," continued the other with irritating
insolence, "but so that you may remember my words and this warning when I
am gone." Then, with a final fling of defiance: "This is the first time you
have seen me, M. Coquenil, and you will probably never see me again, but
you will hear from me. _Now blow your whistle!_"

Coquenil was puzzled. If this was a bluff, it was the maddest, most
incomprehensible bluff that a criminal ever made. But if it was _not_ a
bluff? Could there be a hidden purpose here? Was the man deliberately
making some subtle move in the game he was playing? The detective paused to
think. They had come down the Champs Elysees, past the Ansonia, and were
nearing the Rond Point, the best guarded part of Paris, where the shrill
summons of his police call would be answered almost instantly. And yet he
hesitated.

"There is no hurry, I suppose," said the detective. "I'd like to ask a
question or two."

"As many as you please."

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