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.