ed her personality. Her
perfume was in the air. And now she was gone.

"We won't be here," Alan was repeating. He gripped me at the window.
"Look!" In his hand was an ugly-looking, smokeless, soundless
automatic of the Essen type. "And I've got another, for you. Brought
them up with me."

His face was white and drawn, but his hands abruptly were steady. The
tremble was gone out of his voice.

"I'm going after him. George! Now! Understand that? Now! His place is
only thirty miles from here, out there in the mountains. You can see
it in the daylight--a wall around his property and a stone castle
which he built in the middle of it. A gold mine? Hell!"

There was nothing to be seen now out of the window but the
snow-filled darkness, the blurred lights of lower Quebec and the line
of dock-lights five hundred feet under us.

"Will you fly me, George?"

"Of course."

I was the one trembling now; the cool feel of the automatic which Alan
thrust into my hand seemed suddenly to crystallize Bab's danger. I was
here in her room, with the scent of her perfume around it, and this
deadly weapon was needed! But the trembling was gone in a moment.

"Yes. Of course, Alan. No use talking to the police. You can't get a
search warrant to ransack the castle of a rich man just because you
can't find your sister. Come on. You can tell me what his place is
like as we go."

* * * * *

Bundled in our flying suits we hurried from the hotel, climbed the
Citadel slope of the landing field, and in ten minutes were again in
the air. The wind sucked at us. The snow now was falling with thick
huge flakes. Directed by Alan, I headed out over the ice-filled St.
Lawrence, past the frozen Isle d'Orleans, toward Polter's mysterious
mountain castle.

Suddenly Alan burst out, "I know what father's secret was, George! I
can piece it together now, from little things that were meaningless
when I was a kid. He invented the electro-microscope. You know that.
The infinitely small fascinated him. I remember he once said that if
we could see far enough down into smallness, we would come upon human
life!"

Alan's low tense voice was more vehement than I had ever heard it
before. "It's clear to me now, George. That little fragment of golden
quartz which he wanted me to be so careful of contained a world with
human inhabitants! Father knew it, or suspected it. And I think the
chemical problem on which he was working aimed f