d" 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 language that was unfamiliar to Chet. Yet, even then, it was plain
that he was giving instructions, and he repeated familiar words.

"Harkness," Chet heard him say, and, "--Delacouer--_ja!_--Mam'selle
Delacouer!"

Then, leaving the radio, he said, "Put my ship inside the hangar;" and
the pilot, Max, grounded their own ship to allow the men to leap out
and float into the big building the big aircraft in which Schwartzmann
had come.

"Now close the doors!" their leader ordered. "Leave everything as it
was!" And to the pilot he gave added instructions: "There iss no air
traffic here. You will to forty thousand ascend, und you will wait
over this spot." Contemptuously he kicked aside the