dition, I forbid it!"

The younger man laughed raspingly, as he shook off the hand that
clasped his arm, and for a moment it looked as though the two would
fight, there on that dizzy ledge above the world.

Then Stoddard got control of himself.

"Sorry!" he said. "I see I've got to tell you something, Professor.
You think I'm merely the geologist of this expedition, but in fact I'm
a secret service man from Washington, on the trail of the biggest
diamond-smuggling plot in history--and here is where the trail ends!"

* * * * *

Professor Prescott's astonishment at these words was profound. He
stood there blinking up at Stoddard, scarcely believing he had heard
aright.

"You--you say you are--?"

"A detective, if you want. Anyway, if you've read the papers, you must
know that for the past year or more the diamond markets of the world
have been flooded with singularly perfect stones."

"Yes, I recall reading about that. They were thought to be synthetic,
were they not?"

"By certain imaginative newspaper reporters, not by the experts, for
under the microscope they revealed the invariable characteristics of
diamonds formed by nature--the tiny flaws and imperfections no
artificial means could duplicate."

"But didn't I read something, too, about some anonymous Indian rajah
who was thought to be raising money by disposing of his jewels?"

"More newspaper rubbish! For one thing, British secret service men
traced the rumor down and satisfied themselves there wasn't a rajah in
India unloading any diamonds. For another; no rajah could possibly
have the wealth involved. Why, do you know that since this plot
unfolded, over five million carats' worth have made their
appearance--and that means something like a billion dollars."

"Whew!" whistled the professor.

"Whew is right!" his companion agreed. "And not only have the diamond
markets of the world been disorganized by this mysterious influx, but
the countries involved have lost millions of dollars in revenue, due
to the fact that the gems have been smuggled in without payment of
duty."

"But surely, my dear fellow, you don't connect this gigantic plot with
your discovery of--whatever it is you have discovered?"

"A diamond as big as a house! That's what I've discovered! And I most
surely _do_ connect the plot with it. Did you ever have a hunch,
Professor? Well, I had one--and it's worked out!"

"You leave me more in the dark mome