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.