led roar came from the stern and the blast drove him
straight out for a mile; then he swung and returned. He was nosing up
as he touched the blue--straight up--and he held the vertical climb
till the altimeter before him registered sixty thousand.

Traffic is north-bound only on the sixty-level, and Chet set his ship
on a course for the frozen wastes of the Arctic; then he gave her the
gun and nodded in tight-lipped satisfaction at the mounting thunder
that answered from the stern.

Only then did he read again the message on a torn fragment of
telautotype paper. "Harkness," was the signature; and above, a brief
warning and a call--"Danger--must leave at once. You get ship and
stand by. I will meet you there." And, for the first time, Chet found
time to wonder at this danger that had set the hard-headed,
hard-hitting Walt Harkness into a flutter of nerves.

* * * * *

What danger could there be in this well-guarded world? A patrol-ship
passed below him as he asked himself the question. It was symbolic of
a world at peace; a world too busy with its own tremendous development
to find time for wars or makers of war. What trouble could this man
Schwartzmann threaten that a word to the Peace Enforcement Commission
would not quell? Where could he go to elude the inescapable patrols?

And suddenly Chet saw the answer to that question--saw plainly where
Schwartzmann could go. Those vast reaches of black space! If
Schwartzmann had their ship he could go where they had gone--go out to
the Dark Moon.... And Harkness had warned Chet to get their ship and
stand by.

Had Walt learned of some plan of Schwartzmann's? Chet could not answer
the question, but he moved the control rheostat over to the last
notch.

From the body of the craft came an unending roar of a generator where
nothing moved; where only the terrific, explosive impact of bursting
detonite drove out from the stern to throw them forward. "A good
little ship," Chet had said of this cruiser of Diane's; and he nodded
approval now of a ground-speed detector whose quivering needle had
left the 500 mark. It touched 600, crept on, and trembled at 700 miles
an hour with the top speed of the ship.

There was a position-finder in the little control room, and Chet's
gaze returned to it often to see the pinpoint of light that crept
slowly across the surface of a globe. It marked their ever-changing
location, and it moved unerringly toward a pr