document: ACID BATH
   
  
   By VASELEOS GARSON
   
   
    The starways' Lone Watcher had expected some odd developments
   in his singular, nerve-fraught job on the asteroid. But nothing like the
   weird twenty-one-day liquid test devised by the invading Steel-Blues.
    
  
  
   Jon Karyl
   was bolting in a new baffle
   plate on the stationary rocket engine.
   It was a tedious job and took all his
   concentration. So he wasn't paying too much
   attention to what was going on in other
   parts of the little asteroid.
   
   He didn't see the peculiar blue space
   ship, its rockets throttled down, as it drifted
   to land only a few hundred yards away from
   his plastic igloo.
   
   Nor did he see the half-dozen steel-blue
   creatures slide out of the peculiar vessel's
   airlock.
   
   It was only as he crawled out of the
   depths of the rocket power plant that he
   realized something was wrong.
   
   By then it was almost too late. The six
   blue figures were only fifty feet away, approaching
   him at a lope.
   
   Jon Karyl took one look and went bounding
   over the asteroid's rocky slopes in fifty-foot
   bounds.
   
   When you're a Lone Watcher, and
   strangers catch you unawares, you don't
   stand still. You move fast. It's the Watcher's
   first rule. Stay alive. An Earthship may depend
   upon your life.
   
   As he fled, Jon Karyl cursed softly under
   his breath. The automatic alarm should have
   shrilled out a warning.
   
   Then he saved as much of his breath as
   he could as some sort of power wave tore
   up the rocky sward to his left. He twisted
   and zig-zagged in his flight, trying to get
   out of sight of the strangers.
   
   Once hidden from their eyes, he could cut
   back and head for the underground entrance
   to the service station.
   
   He glanced back finally.
   
   Two of the steel-blue creatures were jack-rabbiting
   after him, and rapidly closing the
   distance.
   
   Jon Karyl unsheathed the stubray pistol
   at his side, turned the oxygen dial up for
   greater exertion, increased the gravity pull
   in his space-suit boots as he neared the
   ravine he'd been racing for.
   
   The oxygen was just taking hold when
   he hit the lip of the ravine and began
   sprinting through its man-high bush-strewn
   course.
   
   The power ray from behind ripped out
   great gobs of the sheltering bushes. But
   running naturally, bent close to the bottom
   of the ravine, Jon Karyl dodged the bare
   spots. The oxygen made the tremendous
   exertion easy for his lungs as he sped down
   the dim trail, hidden from the two steel-blue
   stalkers.
   
   He'd eluded them, temporarily at least,
   Jon Karyl decided when he finally edged off
   the dim trail and watched for movement
   along the route behind him.
   
   He stood up, finally, pushed aside the
   leafy overhang of a bush and looked for
   landmarks along the edge of the ravine.
   
   He found one, a stubby bush, shaped like
   a Maltese cross, clinging to the lip of the
   ravine. The hidden entrance to the service
   station wasn't far off.
   
   His pistol held ready, he moved quietly
   on down the ravine until the old water
   course made an abrupt hairpin turn.
   
   Instead of following around the sharp
   bend, Jon Karyl moved straight ahead
   through the overhanging bushes until he
   came to a dense thicket. Dropping to his
   hands and knees he worked his way under
   the edge of the thicket into a hollowed-out
   space in the center.
   
   
  
   There
   , just ahead of him, was the lock
   leading into the service station. Slipping
   a key out of a leg pouch on the space suit,
   he jabbed it into the center of the lock,
   opening the lever housing.
   
   He pulled strongly on the lever. With a
   hiss of escaping air, the lock swung open.
   Jon Karyl darted inside, the door closing
   softly behind.
   
   At the end of the long tunnel he stepped
   to the televisor which was fixed on the area
   surrounding the station.
   
   Jon Karyl saw none of the steel-blue creatures.
   But he saw their ship. It squatted
   like a smashed-down kid's top, its lock shut
   tight.
   
   He tuned the televisor to its widest range
   and finally spotted one of the Steel-Blues.
   He was looking into the stationary rocket
   engine.
   
   As Karyl watched, a second Steel-Blue
   came crawling out of the ship.
   
   The two Steel-Blues moved toward the
   center of the televisor range. They're coming
   toward the station, Karyl thought grimly.
   
   Karyl examined the two creatures. They
   were of the steel-blue color from the crown
   of their egg-shaped heads to the tips of
   their walking appendages.
   
   They were about the height of Karyl—six
   feet. But where he tapered from broad
   shoulders to flat hips, they were straight up
   and down. They had no legs, just appendages,
   many-jointed that stretched and
   shrank independent of the other, but keeping
   the cylindrical body with its four pairs
   of tentacles on a level balance.
   
   Where their eyes would have been was
   an elliptical-shaped lens, covering half the
   egg-head, with its converging ends curving
   around the sides of the head.
   
   Robots! Jon gauged immediately. But
   where were their masters?
   
   The Steel-Blues moved out of the range
   of the televisor. A minute later Jon heard
   a pounding from the station upstairs.
   
   He chuckled. They were like the wolf of
   pre-atomic days who huffed and puffed to
   blow the house down.
   
   The outer shell of the station was formed
   from stelrylite, the toughest metal in the
   solar system. With the self-sealing lock of
   the same resistant material, a mere pounding
   was nothing.
   
   Jon thought he'd have a look-see anyway.
   He went up the steel ladder leading to the
   station's power plant and the televisor that
   could look into every room within the
   station.
   
   He heaved a slight sigh when he reached
   the power room, for right at his hand were
   weapons to blast the ship from the asteroid.
   
   Jon adjusted one televisor to take in the
   lock to the station. His teeth suddenly
   clamped down on his lower lip.
   
   Those Steel-Blues were pounding holes
   into the stelrylite with round-headed metal
   clubs. But it was impossible. Stelrylite didn't
   break up that easily.
   
   Jon leaped to a row of studs, lining up
   the revolving turret which capped the station
   so that its thin fin pointed at the
   squat ship of the invaders.
   
   Then he went to the atomic cannon's
   firing buttons.
   
   He pressed first the yellow, then the blue
   button. Finally the red one.
   
   The thin fin—the cannon's sight—split in
   half as the turret opened and the coiled nose
   of the cannon protruded. There was a
   soundless flash. Then a sharp crack.
   
   Jon was dumbfounded when he saw the
   bolt ricochet off the ship. This was no ship
   of the solar system. There was nothing that
   could withstand even the slight jolt of power
   given by the station cannon on any of the
   Sun's worlds. But what was this? A piece of
   the ship had changed. A bubble of metal,
   like a huge drop of blue wax, dripped off
   the vessel and struck the rocket of the
   asteroid. It steamed and ran in rivulets.
   
   He pressed the red button again.
   
   Then abruptly he was on the floor of the
   power room, his legs strangely cut out from
   under him. He tried to move them. They lay
   flaccid. His arms seemed all right and tried
   to lever himself to an upright position.
   
   Damn it, he seemed as if he were paralyzed
   from the waist down. But it couldn't
   happen that suddenly.
   
   He turned his head.
   
   A Steel-Blue stood facing him. A forked
   tentacle held a square black box.
   
   Jon could read nothing in that metallic
   face. He said, voice muffled by the confines
   of the plastic helmet, "Who are you?"
   
   "I am"—there was a rising inflection in
   the answer—"a Steel-Blue."
   
   There were no lips on the Steel-Blue's
   face to move. "That is what I have named
   you," Jon Karyl said. "But what are you?"
   
   "A robot," came the immediate answer.
   Jon was quite sure then that the Steel-Blue
   was telepathic. "Yes," the Steel-Blue answered.
  "We talk in the language of the
   mind. Come!" he said peremptorily, motioning
   with the square black box.
   
   The paralysis left Karyl's legs. He followed
   the Steel-Blue, aware that the lens
   he'd seen on the creature's face had a
   counterpart on the back of the egg-head.
   
   Eyes in the back of his head, Jon thought.
   That's quite an innovation. "Thank you,"
   Steel-Blue said.
   
   There wasn't much fear in Jon Karyl's
   mind. Psychiatrists had proved that when he
   had applied for this high-paying but man-killing
   job as a Lone Watcher on the Solar
   System's starways.
   
   He had little fear now, only curiosity.
   These Steel-Blues didn't seem inimical.
   They could have snuffed out my life very
   simply. Perhaps they and Solarians can be
   friends.
   
   Steel-Blue chuckled.
   
   
  
   Jon
   followed him through the sundered
   lock of the station. Karyl stopped for a
   moment to examine the wreckage of the
   lock. It had been punched full of holes as
   if it had been some soft cheese instead of a
   metal which Earthmen had spent nearly a
   century perfecting.
   
   "We appreciate your compliment," Steel-Blue
   said. "But that metal also is found on
   our world. It's probably the softest and most
   malleable we have. We were surprised you—earthmen,
   is it?—use it as protective
   metal."
   
   "Why are you in this system?" Jon asked,
   hardly expecting an answer.
   
   It came anyway. "For the same reason you
   Earthmen are reaching out farther into your
   system. We need living room. You have
   strategically placed planets for our use. We
   will use them."
   
   Jon sighed. For 400 years scientists had
   been preaching preparedness as Earth flung
   her ships into the reaches of the solar system,
   taking the first long step toward the
   conquest of space.
   
   There are other races somewhere, they
   argued. As strong and smart as man, many
   of them so transcending man in mental and
   inventive power that we must be prepared to
   strike the minute danger shows.
   
   Now here was the answer to the scientists'
   warning. Invasion by extra-terrestrials.
   
   "What did you say?" asked Steel-Blue.
  "I couldn't understand."
   
   "Just thinking to myself," Jon answered.
   It was a welcome surprise. Apparently his
   thoughts had to be directed outward, rather
   than inward, in order for the Steel-Blues to
   read it.
   
   He followed the Steel-Blue into the gaping
   lock of the invaders' space ship wondering
   how he could warn Earth. The Space
   Patrol cruiser was due in for refueling at
   his service station in 21 days. But by that
   time he probably would be mouldering in
   the rocky dust of the asteroid.
   
   It was pitch dark within the ship but the
   Steel-Blue seemed to have no trouble at all
   maneuvering through the maze of corridors.
   Jon followed him, attached to one tentacle.
   
   Finally Jon and his guide entered a circular
   room, bright with light streaming from
   a glass-like, bulging skylight. They apparently
   were near topside of the vessel.
   
   A Steel-Blue, more massive than his
   guide and with four more pair of tentacles,
   including two short ones that grew from the
   top of its head, spoke out.
   
   "This is the violator?" Jon's Steel-Blue
   nodded.
   
   "You know the penalty? Carry it out."
   
   "He also is an inhabitant of this system,"
   Jon's guide added.
   
   "Examine him first, then give him the
   death."
   
   Jon Karyl shrugged as he was led from
   the lighted room through more corridors.
   If it got too bad he still had the stubray
   pistol.
   
   Anyway, he was curious. He'd taken on
   the lonely, nerve-wracking job of service
   station attendant just to see what it offered.
   
   Here was a part of it, and it was certainly
   something new.
   
   "This is the examination room," his
   Steel-Blue said, almost contemptuously.
   
   A green effulgence surrounded him.
   
   
  
   There
   was a hiss. Simultaneously, as the
   tiny microphone on the outside of his
   suit picked up the hiss, he felt a chill go
   through his body. Then it seemed as if a
   half dozen hands were inside him, examining
   his internal organs. His stomach contracted.
   He felt a squeeze on his heart. His
   lungs tickled.
   
   There were several more queer motions
   inside his body.
   
   Then another Steel-Blue voice said:
   
   "He is a soft-metal creature, made up of
   metals that melt at a very low temperature.
   He also contains a liquid whose makeup I
   cannot ascertain by ray-probe. Bring him
   back when the torture is done."
   
   Jon Karyl grinned a trifle wryly. What
   kind of torture could this be?
   
   Would it last 21 days? He glanced at the
   chronometer on his wrist.
   
   Jon's Steel-Blue led him out of the alien
   ship and halted expectantly just outside the
   ship's lock.
   
   Jon Karyl waited, too. He thought of the
   stubray pistol holstered at his hip. Shoot my
   way out? It'd be fun while it lasted. But he
   toted up the disadvantages.
   
   He either would have to find a hiding
   place on the asteroid, and if the Steel-Blues
   wanted him bad enough they could tear the
   whole place to pieces, or somehow get
   aboard the little life ship hidden in the
   service station.
   
   In that he would be just a sitting duck.
   
   He shrugged off the slight temptation to
   use the pistol. He was still curious.
   
   And he was interested in staying alive as
   long as possible. There was a remote chance
   he might warn the SP ship. Unconsciously,
   he glanced toward his belt to see the little
   power pack which, if under ideal conditions,
   could finger out fifty thousand miles into
   space.
   
   If he could somehow stay alive the 21
   days he might be able to warn the patrol.
   He couldn't do it by attempting to flee, for
   his life would be snuffed out immediately.
   
   The Steel-Blue said quietly:
   
   "It might be ironical to let you warn
   that SP ship you keep thinking about. But
   we know your weapon now. Already our
   ship is equipped with a force field designed
   especially to deflect your atomic guns."
   
   Jon Karyl covered up his thoughts
   quickly. They can delve deeper than the
   surface of the mind. Or wasn't I keeping a
   leash on my thoughts?
   
   The Steel-Blue chuckled. "You get—absent-minded,
   is it?—every once in a
   while."
   
   Just then four other Steel-Blues appeared
   lugging great sheets of plastic and various
   other equipment.
   
   They dumped their loads and began unbundling
   them.
   
   Working swiftly, they built a plastic
   igloo, smaller than the living room in the
   larger service station igloo. They ranged instruments
   inside—one of them Jon Karyl
   recognized as an air pump from within the
   station—and they laid out a pallet.
   
   When they were done Jon saw a miniature
   reproduction of the service station, lacking
   only the cannon cap and fin, and with clear
   plastic walls instead of the opaqueness of the
   other.
   
   His Steel-Blue said: "We have reproduced
   the atmosphere of your station so that you
   be watched while you undergo the torture
   under the normal conditions of your life."
   
   "What is this torture?" Jon Karyl asked.
   
   The answer was almost caressing: "It is
   a liquid we use to dissolve metals. It causes
   joints to harden if even so much as a drop
   remains on it long. It eats away the metal,
   leaving a scaly residue which crumbles
   eventually into dust.
   
   "We will dilute it with a harmless liquid
   for you since No. 1 does not wish you to die
   instantly.
   
   "Enter your"—the Steel-Blue hesitated—"mausoleum.
   You die in your own atmosphere.
   However, we took the liberty of purifying
   it. There were dangerous elements in
   it."
   
   Jon walked into the little igloo. The
   Steel-Blues sealed the lock, fingered dials
   and switches on the outside. Jon's space suit
   deflated. Pressure was building up in the
   igloo.
   
   He took a sample of the air, found that
   it was good, although quite rich in oxygen
   compared with what he'd been using in the
   service station and in his suit.
   
   With a sigh of relief he took off his helmet
   and gulped huge draughts of the air.
   
   He sat down on the pallet and waited
   for the torture to begin.
   
   The Steel Blues crowded about the igloo,
   staring at him through elliptical eyes.
   
   Apparently, they too, were waiting for the
   torture to begin.
   
   Jon thought the excess of oxygen was
   making him light-headed.
   
   He stared at a cylinder which was beginning
   to sprout tentacles from the circle.
   He rubbed his eyes and looked again. An
   opening, like the adjustable eye-piece of a
   spacescope, was appearing in the center of
   the cylinder.
   
   A square, glass-like tumbler sat in the
   opening disclosed in the four-foot cylinder
   that had sprouted tentacles. It contained a
   yellowish liquid.
   
   One of the tentacles reached into the
   opening and clasped the glass. The opening
   closed and the cylinder, propelled by locomotor
   appendages, moved toward Jon.
   
   He didn't like the looks of the liquid in
   the tumbler. It looked like an acid of some
   sort. He raised to his feet.
   
   He unsheathed the stubray gun and prepared
   to blast the cylinder.
   
   
  
   The
   cylinder moved so fast Jon felt his
   eyes jump in his head. He brought the
   stubray gun up—but he was helpless. The
   pistol kept on going up. With a deft movement,
   one of the tentacles had speared it
   from his hand and was holding it out of
   his reach.
   
   Jon kicked at the glass in the cylinder's
   hand. But he was too slow. Two tentacles
   gripped the kicking leg. Another struck him
   in the chest, knocking him to the pallet. The
   same tentacle, assisted by a new one,
   pinioned his shoulders.
   
   Four tentacles held him supine. The cylinder
   lifted a glass-like cap from the tumbler
   of liquid.
   
   Lying there helplessly, Jon was remembering
   an old fairy tale he'd read as a kid.
   Something about a fellow named Socrates
   who was given a cup of hemlock to drink.
   It was the finis for Socrates. But the old
   hero had been nonchalant and calm about
   the whole thing.
   
   With a sigh, Jon Karyl, who was curious
   unto death, relaxed and said, "All right,
   bub, you don't have to force-feed me. I'll
   take it like a man."
   
   The cylinder apparently understood him,
   for it handed him the tumbler. It even reholstered
   his stubray pistol.
   
   Jon brought the glass of liquid under his
   nose. The fumes of the liquid were pungent.
   It brought tears to his eyes.
   
   He looked at the cylinder, then at the
   Steel-Blues crowding around the plastic
   igloo. He waved the glass at the audience.
   
   "To Earth, ever triumphant," he toasted.
   Then he drained the glass at a gulp.
   
   Its taste was bitter, and he felt hot
   prickles jab at his scalp. It was like eating
   very hot peppers. His eyes filled with tears.
   He coughed as the stuff went down.
   
   But he was still alive, he thought in
   amazement. He'd drunk the hemlock and
   was still alive.
   
   The reaction set in quickly. He hadn't
   known until then how tense he'd been. Now
   with the torture ordeal over, he relaxed. He
   laid down on the pallet and went to sleep.
   
   There was one lone Steel-Blue watching
   him when he rubbed the sleep out of his
   eyes and sat up.
   
   He vanished almost instantly. He, or another
   like him, returned immediately accompanied
   by a half-dozen others, including
   the multi-tentacled creature known as No. 1.
   
   One said,
   
   "You are alive." The thought registered
   amazement. "When you lost consciousness,
   we thought you had"—there was a hesitation—"as
   you say, died."
   
   "No," Jon Karyl said. "I didn't die. I
   was just plain dead-beat so I went to sleep."
   The Steel-Blues apparently didn't understand.
   
   "Good it is that you live. The torture
   will continue," spoke No. 1 before loping
   away.
   
   The cylinder business began again. This
   time, Jon drank the bitter liquid slowly, trying
   to figure out what it was. It had a
   familiar, tantalizing taste but he couldn't
   quite put a taste-finger on it.
   
   His belly said he was hungry. He glanced
   at his chronometer. Only 20 days left before
   the SP ship arrived.
   
   Would this torture—he chuckled—last
   until then? But he was growing more and
   more conscious that his belly was screaming
   for hunger. The liquid had taken the edge
   off his thirst.
   
   It was on the fifth day of his torture that
   Jon Karyl decided that he was going to get
   something to eat or perish in the attempt.
   
   The cylinder sat passively in its niche in
   the circle. A dozen Steel-Blues were watching
   as Jon put on his helmet and unsheathed
   his stubray.
   
   They merely watched as he pressed the
   stubray's firing stud. Invisible rays licked
   out of the bulbous muzzle of the pistol.
   The plastic splintered.
   
   Jon was out of his goldfish bowl and
   striding toward his own igloo adjacent to
   the service station when a Steel-Blue
   accosted him.
   
   "Out of my way," grunted Jon, waving
   the stubray. "I'm hungry."
   
   "I'm the first Steel-Blue you met," said
   the creature who barred his way. "Go back
   to your torture."
   
   "But I'm so hungry I'll chew off one of
   your tentacles and eat it without seasoning."
   
   "Eat?" The Steel-Blue sounded puzzled.
   
   "I want to refuel. I've got to have food
   to keep my engine going."
   
   Steel-Blue chuckled. "So the hemlock, as
   you call it, is beginning to affect you at
   last? Back to the torture room."
   
   "Like R-dust," Jon growled. He pressed
   the firing stud on the stubray gun. One of
   Steel-Blue's tentacles broke off and fell to
   the rocky sward.
   
   Steel-Blue jerked out the box he'd used
   once before. A tentacle danced over it.
   
   Abruptly Jon found himself standing on
   a pinnacle of rock. Steel-Blue had cut a
   swath around him 15 feet deep and five feet
   wide.
   
   "Back to the room," Steel-Blue commanded.
   
   Jon resheathed the stubray pistol,
   shrugged non-committally and leaped the
   trench. He walked slowly back and reentered
   the torture chamber.
   
   The Steel-Blues rapidly repaired the damage
   he'd done.
   
   As he watched them, Jon was still curious,
   but he was getting mad underneath at
   the cold egoism of the Steel-Blues.
   
   By the shimmering clouds of Earth, by
   her green fields, and dark forests, he'd
   stay alive to warn the SP ship.
   
   Yes, he'd stay alive till then. And send
   the story of the Steel-Blues' corrosive acid
   to it. Then hundreds of Earth's ships could
   equip themselves with spray guns and squirt
   citric acid and watch the Steel-Blues fade
   away.
   
   It sounded almost silly to Jon Karyl. The
   fruit acid of Earth to repel these invaders—it
   doesn't sound possible. That couldn't be
   the answer.
   
   Citric acid wasn't the answer, Jon Karyl
   discovered a week later.
   
   The Steel-Blue who had captured him in
   the power room of the service station came
   in to examine him.
   
   "You're still holding out, I see," he observed
   after poking Jon in every sensitive
   part of his body.
   
   "I'll suggest to No. 1 that we increase
   the power of the—ah—hemlock. How do
   you feel?"
   
   Between the rich oxygen and the dizziness
   of hunger, Jon was a bit delirious. But he
   answered honestly enough: "My guts feel as
   if they're chewing each other up. My bones
   ache. My joints creak. I can't coordinate I'm
   so hungry."
   
   "That is the hemlock," Steel-Blue said.
   
   It was when he quaffed the new and
   stronger draught that Jon knew that his
   hope that it was citric acid was squelched.
   
   The acid taste was weaker which meant
   that the citric acid was the diluting liquid.
   It was the liquid he couldn't taste beneath
   the tang of the citric acid that was the corrosive
   acid.
   
   On the fourteenth day, Jon was so weak
   he didn't feel much like moving around. He
   let the cylinder feed him the hemlock.
   
   No. 1 came again to see him, and went
   away chuckling, "Decrease the dilution.
   This Earthman at last is beginning to
   suffer."
   
   
  
   Staying
   alive had now become a fetish
   with Jon.
   
   On the sixteenth day, the Earthman realized
   that the Steel-Blues also were waiting
   for the SP ship.
   
   The extra-terrestrials had repaired the
   blue ship where the service station atomic
   ray had struck. And they were doing a little
   target practice with plastic bubbles only a
   few miles above the asteroid.
   
   When his chronometer clocked off the
   beginning of the twenty-first day, Jon received
   a tumbler of the hemlock from the
   hands of No. 1 himself.
   
   "It is the hemlock," he chuckled, "undiluted.
   Drink it and your torture is over.
   You will die before your SP ship is destroyed.
   
   "We have played with you long enough.
   Today we begin to toy with your SP ship.
   Drink up, Earthman, drink to enslavement."
   
   Weak though he was Jon lunged to his
   feet, spilling the tumbler of liquid. It ran
   cool along the plastic arm of his space suit.
   He changed his mind about throwing the
   contents on No. 1.
   
   With a smile he set the glass at his lips
   and drank. Then he laughed at No. 1.
   
   "The SP ship will turn your ship into
   jelly."
   
   No. 1 swept out, chuckling. "Boast if you
   will, Earthman, it's your last chance."
   
   There was an exultation in Jon's heart
   that deadened the hunger and washed away
   the nausea.
   
   At last he knew what the hemlock was.
   
   He sat on the pallet adjusting the little
   power-pack radio. The SP ship should now
   be within range of the set. The space patrol
   was notorious for its accuracy in keeping to
   schedule. Seconds counted like years. They
   had to be on the nose, or it meant disaster
   or death.
   
   He sent out the call letters.
   
   "AX to SP-101 ... AX to SP-101 ... AX
   to SP-101 ..."
   
   Three times he sent the call, then began
   sending his message, hoping that his signal
   was reaching the ship. He couldn't know if
   they answered. Though the power pack
   could get out a message over a vast distance,
   it could not pick up messages even
   when backed by an SP ship's power unless
   the ship was only a few hundred miles
   away.
   
   The power pack was strictly a distress
   signal.
   
   He didn't know how long he'd been
   sending, nor how many times his weary
   voice had repeated the short but desperate
   message.
   
   He kept watching the heavens and hoping.
   
   Abruptly he knew the SP ship was coming,
   for the blue ship of the Steel-Blues was
   rising silently from the asteroid.
   
   Up and up it rose, then flames flickered
   in a circle about its curious shape. The ship
   disappeared, suddenly accelerating.
   
   Jon Karyl strained his eyes.
   
   Finally he looked away from the heavens
   to the two Steel-Blues who stood negligently
   outside the goldfish bowl.
   
   Once more, Jon used the stubray pistol.
   He marched out of the plastic igloo and ran
   toward the service station.
   
   He didn't know how weak he was until
   he stumbled and fell only a few feet from
   his prison.
   
   The Steel-Blues just watched him.
   
   He crawled on, around the circular pit in
   the sward of the asteroid where one Steel-Blue
   had shown him the power of his
   weapon.
   
   He'd been crawling through a nightmare
   for years when the quiet voice penetrated
   his dulled mind.
   
   "Take it easy, Karyl. You're among
   friends."
   
   He pried open his eyes with his will. He
   saw the blue and gold of a space guard's
   uniform. He sighed and drifted into unconsciousness.
   
   
  
   He was
   still weak days later when
   Capt. Ron Small of SP-101 said,
   
   "Yes, Karyl, it's ironical. They fed you
   what they thought was sure death, and it's
   the only thing that kept you going long
   enough to warn us."
   
   "I was dumb for a long time," Karyl said.
  "I thought that it was the acid, almost to
   the very last. But when I drank that last
   glass, I knew they didn't have a chance.
   
   "They were metal monsters. No wonder
   they feared that liquid. It would rust their
   joints, short their wiring, and kill them.
   No wonder they stared when I kept alive
   after drinking enough to completely annihilate
   a half-dozen of them.
   
   "But what happened when you met the
   ship?"
   
   The space captain grinned.
   
   "Not much. Our crew was busy creating
   a hollow shell filled with water to be shot
   out of a rocket tube converted into a projectile
   thrower.
   
   "These Steel-Blues, as you call them, put
   traction beams on us and started tugging us
   toward the asteroid. We tried a couple of
   atomic shots but when they just glanced off,
   we gave up.
   
   "They weren't expecting the shell of
   water. When it hit that blue ship, you could
   almost see it oxidize before your eyes.
   
   "I guess they knew what was wrong right
   away. They let go the traction beams and
   tried to get away. They forgot about the
   force field, so we just poured atomic fire
   into the weakening ship. It just melted
   away."
   
   Jon Karyl got up from the divan where
   he'd been lying. "They thought I was a
   metal creature, too. But where do you suppose
   they came from?"
   
   The captain shrugged. "Who knows?"
   
   Jon set two glasses on the table.
   
   "Have a drink of the best damn water in
   the solar system?" He asked Capt. Small.
   
   "Don't mind if I do."
   
   The water twinkled in the two glasses,
   winking as if it knew just what it had
   done.
question_text: What is the plot of the story?
response: After he repairs the rocket engine, Jon Karyl, a starways’ Lone Watcher, notices the invasion of Steel-Blues, extraterrestrial robotic creatures. He flees towards the service station while six Steel-Blues chase behind him. During his run, Steel-Blues use power rays to attack him but fail. He flees successfully into the service station, uses the televisors to spot the motion of Steel-Blues, and examines them. He realizes Steel-Blues are robotic. The pounding sound upstairs makes Jon realizes that Steel-Blues is trying to break the entrance door. He thinks Steel-Blues are doing a useless job as the strongest metal forms the service station in the solar system. He goes to the station’s power plant to use the televisor that can see every room, but the Steel-Blue pounds a hole into the door, which seems impossible to him. He attacks the Steel-Blues’ spaceship with an atomic cannon bomb, finding the bomb ricochet off the ship and strike the rocket nearby. Suddenly, he is taken down by the Steel-Blue, who invades the station when he tries to attack the ship the second time. Through the conversation with the invading Steel-Blue, Jon knows that they can read his mind when it is directed outward.
  
  As Jon is taken to the Steel-Blues’ ship, he learns that the toughest metal in the solar system is considered the most vulnerable one for Steel-Blues. He also knows that Steel-Blues’ purpose in invading the solar system is to conquer more living spaces for themselves. In the Steel-Blues’ ship, Jon sees the leader of the Steel-Blue, who orders Jon’s guide Steel-Blue to examine Jon. After Jon is examined, they classify him as a soft-metal creature by him. Jon is taken to a prison to undergo the torture built by the Steel-Blue, forced to drink a liquid used to dissolve the metal. The Earth space patrol cruiser will come to refuel their ship after 21 days; Jon knows that he has to stay alive until then to alert the SP ship. During the torture, namely drinking the unknown liquid, Jon attempts to escape but fails. The Steel-Blues every day watch him undergo torture. At the beginning of the torture, the liquid is diluted and tastes like some strong acid. As the days pass, the diluted portion decreases, and Jon realizes what the liquid is. Finally, on the last day, when the SP ship is scheduled to come, and Jon is fed with the undiluted liquid, he realizes that it is water and the weakness of the Steel-Blues. He sends the message to the SP ship and then passes out outside the prison. When he wakes up, he is rescued by the SP ship, and the Steel-Blues is destroyed by the powerful water attack of the SP ship.
  