"You're afraid of your own shadow!" Miles snarled over his shoulder to
Charley Brett who followed him out of the room. Brett was adjusting his
oxygen mask with one hand and gripping a paralo-ray gun tightly with the
other.
"Never mind the cracks," snapped Brett, his voice muffled by the mask.
"I tell you I heard someone moving around in here."
Miles laughed again and walked straight to the middle of the room. With
their backs pressed to the wall beside the door, Tom and Astro saw Miles
bend over and lift a trap door in the middle of the floor.
The two men flashed a light down into the opening and climbed down,
pulling the trap door closed after them.
No sooner was it shut than Tom and Astro jumped forward to examine it
cautiously. Astro started to pull it open but Tom held out a warning
hand. He turned and pointed toward the room that Miles and Brett had
left. Astro nodded and they walked quickly back to the door. Sliding it
open, they stepped inside.
"By the rings of Saturn!" cried Astro.
"Well, blast my jets!" Tom exclaimed.
The air in the room was clear, completely free of the misty whirling
methane ammonia of death that swirled around them outside. Recovering
from his surprise quickly, Astro closed the door and walked to the
center of the room, looking around curiously. Tom had already slipped
off his mask and was examining the equipment lying on the floor. Astro
bent over an oddly shaped machine that looked somewhat like an ancient
compressed-air drill, with a long bar protruding from one end. He
examined the bar closely and then turned slowly to Tom.
"Do you know what this machine is?" he asked in almost a whisper.
Tom looked at it and then shook his head.
"I haven't seen one of these since I left Venus, and then only when I
was a kid hanging around the spaceports where the space rats used to
blast off for the asteroids looking for uranium."
"You mean you hunt uranium with that thing?" asked Tom.
"No, you dig it out with this."
Tom gazed at the machine thoughtfully. "Why would it be here?" he mused.
"It's already been used," said Astro, standing up. "Look, the drill head
is dull."
"That trap door!" Tom exclaimed. "It leads to a mine. Miles and Brett
have discovered high-grade uranium right here on Titan where everyone
thought there was nothing but _crystal_!"
Astro nodded grimly. "And that isn't all. This room is free of ammonia
gas."
"But how in the star-blazing dickens can they keep it out of here when
everything else outside is flooded with it?" asked Tom.
Astro spun around and began to examine the walls. "Just as I thought!"
he exclaimed. "This room is airtight! Sealed! Oxygen is being pumped in
here."
"From where?"
"Might be from somewhere below," replied the big Venusian. "Down that
trap where Miles and Brett went."
Tom put his mask back on and headed for the door. Astro followed him.
They opened it a little and peered into the swirling mist.
"Then it's being pumped in directly," Tom asserted. "Through a duct
leading directly up into this room from somewhere below."
Astro nodded. "Then there's only one thing left to do. Go down through
that trap door and see what we can find." He stepped forward.
"Wait a minute, Astro," said Tom, stopping him. "Let me check our
oxygen. There might not be any down there. Remember, Miles and Brett
wore _their_ masks."
Making a quick check of their oxygen supply, Tom patted Astro on the
back and started forward. "It's O.K. We've got another four hours left.
Come on!"
They moved toward the trap door slowly.
"I still wish I had a ray gun," whispered Tom.
"As long as I can use these"--Astro balled his hamlike hands into
fists--"we're O.K."
When they reached the trap door, Tom got down on his knees and felt
around for the opening. He found a small ring bolt, motioned to Astro to
step back, and pulled. The trap door swung back easily and a shaft of
white light gleamed in his face. The young cadet leaned down and looked
through the opening. What he saw made him gasp.
"What is it?" demanded Astro.
[Illustration: _Tom got down on his knees and felt around for an
opening_]
Tom motioned for him to get down and look. The big cadet dropped lightly
to his knees to peer through the opening. "By the moons of Jupiter," he
exclaimed, "it's a--a mining shaft!"
"Just what we thought it was," whispered Tom. "Come on. Let's go down
and find out where it leads."
"Maybe we'd better go back and tell Captain Strong about this first,"
Astro said speculatively.
"There's no telling what Brett and Miles are liable to do while we're
gone," said Tom. "You find Captain Strong and I'll go down into the
shaft and look around."
"Not on your life," protested Astro. "You don't think I'd let you go
down there alone, do you? _You_ go back to Captain Strong and _I'll_ see
what those two are doing down there."
Tom grinned. "O.K., we'll both go down," he said.
Opening the trap door all the way, Tom eased himself down into the
opening. Astro followed. Immediately below the trap, they found a
ladder, fixed to the wall of the shaft, which led directly down to a
point about thirty feet below the surface of Titan. At the bottom the
two cadets paused. A long tunnel stretched before them.
"Listen to that!" exclaimed Astro.
Tom ripped off the mask and listened. He heard a strange noise which
sounded more like the roar of escaping gas than a motor.
"What is it?" asked Tom.
"That's what I'd like to know!"
"And that light," continued Tom, pointing down the length of the tunnel.
"Do you suppose it's Miles and Brett?"
"It isn't moving," commented Astro.
"Well, since we're here we might as well find out as much as we can,"
Tom decided. "Let's go."
The two cadets flattened themselves against the side of the shaft and
inched forward. The hissing noise was slowly building up to a roar now,
and as they made their way along the shaft, they passed other smaller
tunnels that branched off to the left and right. There was evidence of
recent work. Tools were scattered along the tunnel floors, as if the
workers had dropped them in sudden flight.
The light ahead of them grew brighter, and as they rounded a corner,
they saw a bare, unshaded lamp suspended from the roof of the tunnel.
Tom suddenly stopped and jerked Astro back. "Look!" he exclaimed,
pointing to the floor, not two paces away. A thin wire, hardly
noticeable, was stretched across the floor at ankle height.
"That bright light is to attract your attention while you trip over that
thing and probably blow yourself to bits," he said grimly, pointing to
the wall where the wire was connected to a small charge of explosives.
"Nothing to bring the roof down," he continued, "but enough to blast
whoever tripped over this wire."
Stepping over the wire carefully, they started down the shaft again, but
Tom paused thoughtfully.
"What's the matter?" asked Astro.
"That booby trap," said Tom. "We'd better not take any chances of
tripping over it on the way back. We might be in a hurry."
"I know what you mean," grunted the big Venusian. He knelt down beside
the menacing box of explosives and quickly disconnected the trip wire,
throwing the box to one side.
Straightening up, Astro announced, "It's harmless now."
Cautiously the two cadets continued down the tunnel, the roaring sound
growing louder and louder. After twenty minutes, Astro paused, his
homely features wrinkled in a frown of worry.
"Think maybe Miles and Brett went off into one of the other side
tunnels?" he asked.
Tom thought a moment. "No, I don't, Astro. We haven't hit another side
tunnel since we passed that booby trap back there. What would be the use
of setting that thing up if they went in another direction?"
"There must be another way out of here, then," Astro remarked.
"Why?"
"That part of the tunnel back there by the bomb was loose dirt. If the
bomb had exploded, the whole tunnel would have been blocked off and how
could they get out?"
Tom didn't answer. He was thinking about what he was going to do if
there should be another booby trap in the tunnel. It was so dark now
that they could hardly see more than a few feet ahead. The bright light
was merely a pinpoint in the distance behind them.
And then Tom became aware that the roar that had been with them
constantly since they had entered the shaft had now lessened in volume.
But they had not passed a single branch-off tunnel where the sound could
have originated. Tom made up his mind quickly.
"Come on, Astro," he said. "We're going back."
"Why?"
"I haven't time to explain now, but you walk close to one side of the
shaft and I'll take the other. Feel along with your hands for anything
like a door or an opening. I think we've passed them."
Without another word, Astro turned around and headed back, feeling along
the tunnel wall.
It did not take the two cadets long to discover what they were looking
for. A heavy wooden door was set flush with the side of the tunnel. And
when Tom pressed his ear to it, he could hear the roaring sound
throbbing heavily inside.
"See if you can open it, Astro," said Tom. "But take it easy."
Astro felt along the side of the door until he found a wooden latch and
he lifted it gently. The door swung back, as if pushed, as a powerful
draft caught it from the other side. The roar was now deafening.
Tom stepped inside cautiously, followed by Astro. They found themselves
on a small balcony overlooking a huge subterranean room. In the room
they saw Quent Miles and Charles Brett bending over a table on which
were several delicate electronic instruments. Tom and Astro recognized
them immediately as testing machinery for radioactivity, much more
advanced and sensitive than the ordinary Geiger counter. Around the two
men was ample evidence of Astro's original assumption that they were
digging into a hot vein of uranium pitchblende. To one side of the room,
lead sheets lined a rough boxlike structure that Astro and Tom guessed
was covering for the radioactive vein. Against the wall lay the
lead-lined suits used by the miners. Further to one side, Tom saw a
huge open pipe. He nudged Astro.
"Look, over there," Tom whispered. "That's where the oxygen is coming
from!"
Below them, Miles suddenly walked to the pipe and pulled a large lever
on its side. The roaring sound stopped immediately and the boys felt the
air pressure in the room lessen slightly.
"That blasted noise is driving me crazy," explained Miles, walking back
to the table, his voice echoing in the rock-walled cavern.
Brett, leaning over the table, was stabbing around futilely in one of
the sets of tubes in a complicated testing device. "Wish we had that
squirt Manning here," he mumbled. "He could fix these things up in no
time at all."
"I could always go back to the hide-out and get him," suggested Miles.
On the balcony Tom gripped Astro's arm tightly.
"Astro! Did you hear that?" he exclaimed.
The big cadet nodded and started to rise from their place of
concealment. Tom pulled him down. "Wait," he whispered sharply. "No use
barging in on them yet. Maybe we can find out where Roger is first."
Astro reluctantly crouched down again, his hamlike hands balled into
fists.
The two cadets watched Quent Miles and Brett work on the instruments
awhile longer. Finally Miles slammed down a pair of wire cutters on the
table and growled at Brett. "No use messing with this thing any longer.
I don't know what makes it tick, so I can't find the trouble. We need
new equipment."
"It'll take at least two weeks to get new equipment the way things are
going here at Titan," replied Brett.
"Well, there's no use hanging around here if we can't dig any more of
the stuff out, and I ain't going behind that lead shield unless I got a
machine that tells me it's safe."
"I've been thinking about Manning," said Brett.
"What about him?"
"Suppose we move the stuff we've already mined to the hide-out, and take
this equipment along too. He can repair it out there. We can turn off
the oxygen that we're sucking off from the Solar Guard pumps, and by the
time we get back here, the old satellite will be back to normal. Then,
with the equipment repaired and Olympia back to normal, we can really
begin operations."
Quent nodded quickly. "Good idea. Come on. Let's get this stuff aboard
the ship."
On the balcony Tom and Astro looked at each other.
"They're responsible for what's happened here on Titan!" whispered Tom.
"They have been sucking off oxygen from the main pumps supporting the
force field."
"Come on, Tom," growled Astro. "My fist is just itching to make contact
with a couple of no-good chins."
"Not so fast! We still don't know where they've got Roger."
"You want to keep on following them?" asked Astro.
"At least to their ship," Tom replied. "Then we can notify Captain
Strong and he can track them in the _Polaris_. If we barge in on them
now, we'll just get the satisfaction of knocking their heads together
with no guarantee of any information." The young cadet turned to the
door. "We'll sneak up the tunnel a way and then follow them out."
"Hurry!" said Astro. "Here they come." Quent, carrying one of the
instruments, had started up the steps to the balcony.
Tom grabbed the latch and pushed up but the door would not open. "Give
me a hand, Astro, quick!" he called.
Astro grabbed the latch and heaved his bulk against the door. Suddenly
he stepped back dumfounded, holding the latch in his hand. It had
snapped off.
Just at that moment Brett looked up and saw them. He shouted a warning
to Miles, who dropped the instrument he was carrying and pulled out his
ray gun.
"Just stand where you are!" he snarled, leveling the gun at them.
Tom and Astro stood quietly, hands in the air.
"How in blazes did they get here?" Brett cried.
"They must have followed me," said Miles. "They certainly couldn't have
known about this place."
"But how did they get past the trap?" Brett persisted, still amazed and
shaken by the unexpected appearance of the cadets.
Astro snorted his contempt. "You must think we're a couple of prize
space jerks," he growled. "You can't even kill a mouse with that thing
now."
"Let's cut the talk," said Miles. "What do we do with them?"
"Freeze them!" snapped Brett. "No telling how long they've been here and
how much they know."
"We know enough to put you on a prison asteroid," challenged Tom.
"Freeze 'em, it is," said Quent. "We'll get the ship loaded and decide
what to do with them later."
He pressed the trigger on his ray gun. There was a harsh crackling sound
and Tom and Astro stiffened into immobility, every nerve and muscle
deadened. With the exception of their hearts, and sense of seeing and
hearing, they might have been dead men.
Laughing to themselves, Quent Miles and Charles Brett picked up their
instruments, walked past them, and disappeared through the door.
[Illustration]