s pull was nullified, had been the air-lanes for fast
liners. Empty lanes they were now; for the R. A., as the flying
fraternity knew it--the Heaviside Layer of an earlier day--marked the
danger line above which the mysterious serpents lay in wait. Only the
speed of Chet's ship saved them; more than one of the luminous monsters
was in sight as he plunged through the invisible R. A. and threw on
their bow-blast strongly to check their fall.

Then, as he set a course that would take them to that section of the
Arctic waste where the ship had been, he pondered once more upon the
subject of this Schwartzmann of the shifty eyes and the glib tongue and
of his men who had "got out of hand" and had captured this ship.

"Why in thunder are we back here?" Chet asked himself in perplexity.
"This big boy means to keep the ship; and, whatever his plans may have
been before, he will never stop short of the Dark Moon now that he has
seen the old boat perform. Then why didn't he keep on when he was
started? Had the serpents frightened him back?"

He was still mentally proposing questions to which there seemed no
answer when he felt the pressure of a metal tube against his back. The
voice of Schwartzmann was in his ears.

"This is a detonite pistol"--that voice was no longer unctuous and
self-deprecating--"one move and I'll plant a charge inside you that will
smash you to a jelly!"

* * * * *

There were hands that gripped Chet before he could turn; his arms were
wrenched backward; he was helpless in the grip of Schwartzmann's men.
The former pilot sprang forward.

"Take control, Max!" Schwartzmann snapped; but he followed it with a
question while the pilot was reaching for the ball. "You can fly it for
sure, Max?"

The man called Max answered confidently.

"_Ja wohl!_" he said with eager assurance. "Up top there would have been
no trouble yet for that _verdammt, verloren_ valve. That one
experimental trip is enough--I fly it!"

Those who held Chet were binding his wrists. He was thrown to the floor
while his feet were tied, and, as a last precaution, a gag was forced
into his mouth. Schwartzmann left this work to his men. He paid no
attention to Chet; he was busy at the radio.

He placed the sending-levers in strange positions that would effect a
blending of wave lengths which only one receiving instrument could pick
up. He spoke cryptic words into the microphone, then dropped into a
languag