e ride in this machine of yours, Professor. Down. About
four miles. I'll have to ask you to do the driving. You will, won't
you--without making a fuss?"

Guinness's face worked furiously. "Why, you're crazy, Quade!" he
sputtered. "I certainly won't!"

"No?" asked Quade softly. The automatic he held veered around, till it
was pointing directly at the girl. "I wouldn't want to have to shoot
Sue--say--through the hand...." His finger tightened perceptibly on
the trigger.

"You're mad, man!" Guinness burst out. "You're crazy! What's the
idea--"

"In due time I'll tell you. But now I'll ask you just once more,"
Quade persisted. "Will you enter that borer, or must I--" He broke off
with an expressive shrug.

David Guinness was powerless. He had not the slightest idea what Quade
might be about; the one thought that broke through his fear and anger
was that the man was mad, and had better be humored. He trembled, and
a tight sensation came to his throat at sight of the steady gun
trained on his daughter. He dared not trifle.

"I'll do it," he said.

* * * * *

James Quade laughed. "That's better. You always were essentially
reasonable, though somewhat impulsive for a man of your age. The rash
way you severed our partnership, for instance.... But enough of that.
I think we'd better leave immediately. Into the sphere, please. You
first, Miss Guinness."

"Must she come?"

"I'm afraid so. I can't very well leave her here all unprotected, can
I?"

Quade's voice was soft and suave, but an undercurrent of sarcasm ran
through it. Guinness winced under it; his whole body was trembling
with suppressed rage and indignation. As he stepped to the door of the
earth-borer he turned and asked:

"How did you know our plans? About the radium?--the borer?"

Quade told him. "Have you forgotten," he said, "that you talked the
matter over with me before we split last year? I simply had the
laboratory watched, and when you got new financial backing from young
Holmes, and came here. I followed you. Simple, eh?... Well, enough of
this. Get inside. You first, Sue."

Trembling, the girl obeyed, and when her father hesitated Quade jammed
his gun viciously into his ribs and pushed him to the door. "Inside!"
he hissed, and reluctantly, hatred in his eyes, the professor stepped
into the control compartment after Sue. Quade gave a last quick glance
around and, with gun ever wary, passed inside. The door slamm