They spent much of that night in going over their plans. Ketrik had no misapprehensions about landing on Mars; he could do that despite Vaajo's patrols. Turibek presented the real problem.

Carefully he perused the tele-strip recordings from Mark's operatives, E-39 and EV-5. There had only been two reports, and they were brief.

"This last one was sent two weeks ago," Mark said, "and I haven't been able to contact them since. The channel's dead. I'm afraid it means their hide-out was discovered!"

Ketrik studied the rough map Mark had made, showing the location of the hide-out in the K'Mari Range, and its position from Turibek.

"This will help. I'll try to get over there, see if anything's left of their sending equipment. Then I want to make a try for the city. If I can get inside of Turibek, and maybe get a line on this scientific thing they're working up ... I was at Turibek eight years ago, and know it fairly well."

"Here's a photo-static air view," Mark said. "Afraid it doesn't show much."

"It shows one thing," Ketrik said, studying the film. "Dar Vaajo's had a wall built completely around the city. That wasn't there eight years ago! And those towers stationed around the wall—what do you suppose they are?"

"Control towers. That's an electronic wall! And you'll observe there's another within the city itself, surrounding that group of buildings which must be the laboratories. Ketrik—if you ever get in there...." His voice dwindled away in doubt.

"You don't think I can do it? I don't either, Mark—not as an Earthman!"

"Come. We'll fix that."

They passed through endless corridors, arrived finally at a large white-enameled room. It was complete with operating tables, instruments, plastics, ray-lamps—everything necessary to Earth's espionage system.

Ketrik stripped piecemeal, allowed every inch of his superbly muscled body to be subjected to the stinging Ulmo lamps. Gradually under the hot rays, the very pigmentation of his skin changed to the deep reddish-copper of a Martian. Mark proved himself an expert at this. Even the insides of Ketrik's ears did not escape the ray.

"Don't worry," Mark told him. "This will all wear off eventually."

"Yes? How long?"

"In about two years! Now, your eyes. You never saw a Martian with gray eyes. Look up just a moment."

A few drops of liquid, a harmless vegetable composition, changed Ketrik's eyes to a muddy golden color.

"Those bangs have got to come off!" Mark went to work in earnest. Ten minutes under another ray, and Ketrik's unruly hair was transformed into tight, crisp curls in keeping with the Martian fashion. His features presented the hardest problem, but Mark worked miracles with the plastics and equipment.

At last the job was done. When Ketrik surveyed himself in the mirror he saw a tall, somewhat arrogant Martian of the middle class, with slightly flaring nostrils, bulging cheek-bones and lips curving in a thin, cruel smile. He nodded, more than satisfied.

Mark consulted his wrist-chrono. "Four hours until dawn. Better grab a few hours' sleep, it may be your last for a while."

"Sure, but I'll rest better if I know one thing. Where's my ship?"

"My guards moved it secretly to the underground repair locks. Right now it's undergoing as radical a change as I just performed on you." Mark smiled. "When you leave Earth, it will be in a slow-powered ore freighter ostensibly bound for the Moon!"

An hour before the dawn, Mark wakened Ketrik. But Mark hadn't been idle in those hours. He handed the other a small, compact instrument.

"Here's a Scanner disc I just finished assembling. It only works within a very short range, but you may have need of it."

They took the swift tube-car across the city and arrived at the spaceport amidst surprising activity. A Callistan freighter had just berthed. Bright lights were trained upon it, men and trucks were moving about handling the cargo.

"I planned it for this hour," Mark explained, "because now less attention will be drawn to you. We can't be too careful." He pointed to a dark, far corner of the field where a clumsy bulk rested. "Believe it or not, that's your ship. The exterior's been changed but that's all. You still have the Frequency Tuner." They paused for a moment in solemn thought. "I can't impress upon you too much, Ketrik, what this—"

"That's right, Mark, you can't. So let's not mention it." Ketrik was brusque. "Believe me, son, I know what I'm up against."

"Send any news at all as to what Dar Vaajo's up to. If I learn that, I can rouse the people of Earth to preparedness in spite of the Council." He thrust out his hand. "I'll say goodby now—and good luck!"

Ketrik said simply, "You'll be hearing from me, Mark." He moved across the field, keeping to the shadows, the collar of his space tunic turned up. He wondered how many of the men working about this field were Martian "Specials." Some of them, surely. If he, an Earthman, could be molded into Martian guise, Dar Vaajo could certainly perform the same miracle in reverse and probably had.

He reached his ship undetected. All was dark and quiet. The hull, he noticed, had been painted solid black. He entered and flicked on the lights. Mark was right, nothing on the inside had been changed.

He explored the ship to make sure. Then he moved forward to the control-console, remembering that this was supposed to be a clumsy Moon freighter. The rockets roared. The ship moved with slow acceleration up the step locks, to finally catapult into the stratosphere.

And five minutes later, just as he was clearing Earth's gravity, he heard the voice behind him:

"Well, Ketrik, at last! Really—I thought you were never going to make it!"

Ketrik had long since learned caution in these matters. He turned slowly now and was glad he did. The first thing he saw was the gun—a powerful weapon, an electro. The fist wrapped around it looked firm and experienced. Ketrik's gaze went to the man's face.

It was the Captain of the Guard, the same captain who had met him at his landing eight hours before. The man was cold-eyed now. He kept a few paces away from Ketrik.

Ketrik said, "I searched the ship. Where were you?"

"You failed to look in the emergency fuel locker. It was a tight squeeze for me." He smiled tightly, surveying Ketrik's transformed figure. "A nice job. Slightly tall for a Martian but, withal very nice. Too bad all that ingenuity has to be wasted at the very outset."

Ketrik's muscles tightened. As though it were a signal, the other's voice became brittle.

"Up! Up with those hands, Ketrik. I have a few questions to ask, and then—"

It seemed ridiculously easy, the way Ketrik did it. He let his eyes go dull. He sighed and raised his hands, slowly. He saw the other's gun-fist relax ever so slightly. Then Ketrik's legs gave way and he went swiftly downward. The captain fired but Ketrik wasn't there, his powerful muscles had launched him forward, beneath the hissing beam. His shoulder caught the other just below the midriff and bent him double, carried him backward. They crashed into the controlroom door. Ketrik's left hand found the other's gun-wrist and twisted powerfully. A bone snapped, the electro skidded away. The captain began a curse but it was cut short by Ketrik's right hand at his throat.

Ketrik pulled the man to a sitting posture. He gazed deep into the eyes which were glazing over with pain. But it was not enough to prevent the true color from shining through ... the color of dull, tarnished gold.

"I thought so," Ketrik murmured, and then his hand loosened, balled into a fist that drove forward. The man laid back and went limp.

Ketrik's fingers probed the other's face. The man was a Martian, all right, the features had been subtly altered. Enough to fool even Mark! Captain of the elite guard! How long had the man masqueraded in that position, Ketrik wondered—and then he shrugged. It didn't matter now.

He went through the man's clothes, found nothing of interest until he came under the left arm-pit. There, next to the skin, he found a tiny metal disk. He rose, went over to the wall-light to examine his find. The disk was perforated with queer Martian characters. Ketrik knew Martian, but he couldn't quite make these out. He bent closer.

A sixth sense warned him, or perhaps it was some slight sound. He whirled. The Martian's hand had moved, was now grasping the electro which he swung up into line. Ketrik's hand dropped and he fired his own heat-beam from the hip. The beam cut a clean swath across the other's chest, and he died without so much as a sigh.

"Sorry, buddy, whoever you are," Ketrik whispered. "Guess I'd have had to do that anyway, though. When Dar Vaajo plants Specials like you on Earth, we don't play for fun!"

He fastened the identification disk under his own arm-pit. Five minutes later, from the starboard lock, he dumped the body into space and without a qualm, rayed it to dust.

Then, champing with impatience, Ketrik allowed his "freighter" to plod Moonward. He skirted within five thousand miles of it, then with the satellite as a shield between him and Earth, he charted for Mars.

His brush with the Martian operative had sobered him. He began to realize that Mark had every reason for alarm! The subtle tampering with the Council's mental patterns, the placing of operatives in high Earth positions, the secret scientific experiments on Mars—they all had to tie in. He was sure of one thing now. Dar Vaajo, an embittered old man, was making one last bid which would bring his race to its former glory or else carry it forever to extinction with him.

There were surely other Martian operatives on Earth, and they would have established a communications base. By this time they had undoubtedly flashed the news of his coming. Ketrik smiled inwardly. Very well—they'd be expecting him at Turibek, but he'd take the indirect approach.

All the way to Mars his mind was at work. He was remembering days he'd spent in that wild desert country of South Mars. From the tide of his thoughts he segregated events ... places and people ... the canals and cruel deserts, the customs of the Rajecs, those fierce black outcasts from the cities of Mars. He knew that before he got through to Turibek, he'd need all this. Already a plan was forming....

Twenty hours later he sighted a Mars patrol, six formidable spacers athwart the Earth-route. They moved leisurely, in perfect formation, and Ketrik knew their network of "finder beams" covered a large area. However, the power-principle of the Frequency Tuner defied those "finders." No challenge came through his open radio, which meant they hadn't sighted him yet.

A solid black ship was strictly against the Space Code, but Codes mattered little now! With the ebony backdrop of space behind him, Ketrik's ship would be hard to detect. He decided to try a sneak past them. He'd have to go into Inferior-plane, but he was sure he could make it.

Quickly he changed course, swept into a sharp parabola that carried him far below the Ecliptic. In a matter of minutes he was watching the Mars-cruisers fade away into darkness. His present course would bring him far over into Mars' dark-side, but that was what he wanted anyway.

Hours later the vast South Desert was rising up below him. Deimos had just appeared, climbing with slow majesty across the sky; Phobos would come a few hours later, pursuing its reckless course. Ketrik peered far ahead to the horizon. There, against the dark downward curve, he saw a faint glow that was not the glow of Deimos. He knew that must be the capital city, Turibek, untold miles away. He made swift calculation. To the right, then, would be the K'Mari Range. He knew those mountains. It would be the very place to leave his ship.

He dropped lower and headed for there. The pale ghost-glow of Deimos didn't help much. He switched to infra-red, peered at the V-Panel as it lighted up and saw the unmistakable, serrated line of mountains about twenty miles away. He had judged it that close! Ketrik grinned proudly.

It was short-lived. A Martian voice sliced through the radio, shrill and commanding.

"Ground! You, below there—you will ground immediately or we blast!"

Then Ketrik realized that for the past several minutes there had been a faint humming sound from above and all about him, scarcely heard. He had relaxed in his vigilance, and the Martian 'copters had picked out his trail—those fast-powered and deadly scouting ships. They too must be equipped with infra-red!

Even as these thoughts raced through his mind, Ketrik was acting. He leaped away from the V-Panel, grabbed the Control and threw it over. Too late now! The ship responded, but sluggishly. The nose veered sharply upward, trying to leap away—then the entire hull shuddered. Power-beams! It must be a vast concentration of them, to stop Frequency power! Slowly his forward progress was retarded. Relentlessly he was being forced down into the Martian sands. Again the voice sliced through.

"It is useless, outlaw! We've had you in our finder for the past five minutes and you are in a network of Power-beams. Nullify your control immediately or we blast!"

Ketrik cursed. Already his ship was straining at the seams. And now he felt insufferable heat all about him, realized they were using the beams. His stomach turned over as he thought of his rocket-tubes loaded with fuel....

Quickly he entered the starboard lock; stood peering down. He was dropping fast. Above him now he saw hosts of vague shapes, heard the whine of Martian 'copter blades cutting the air. The metal under his fingers was growing hot. He counted to five, slowly ... and leaped outward.

It may have been thirty feet—or fifty. Ketrik only knew that he was plummeting downward. He let his muscles go limp, and just in time. He hit the sand hard, rolled over once and knew that no bones were broken. Above him he saw the pale glow of heat-beams, saw the hull of his spacer growing cherry-red ... and suddenly realized his danger.

He staggered up, went ploughing across the desert, still mentally counting off the seconds ... "eight ... nine ... ten...." The explosion lighted the sky for a hell-filled moment. Ketrik went hurling forward, to land head foremost into the sand. Parts of his ship came thudding down about him.

One fragment, red-hot, landed against his arm and burned it severely. Other fragments scattered over a wide area. Ketrik was cursing now, unconsciously using the mono-syllabic Martian in which he had versed himself.

Then it was all over. Ketrik was glad of only one thing. His ship was gone, but the Frequency Tuner had gone with it! The Martians would never get that priceless power unit. He rolled to his back and looked up.

It was not over! A few 'copters were descending to view the wreckage—or perhaps to look for him. Had they seen him jump? Powerful searchlights began criss-crossing the area. Again he staggered up, went forward into darkness. Every muscle ached, but his eyes were alert for the beams. Whenever one passed near him, he flattened into the sand. After untold agonies, he judged that he was fairly safe. Far behind, he heard the drift of excited Martian voices.

He didn't rest. He kept going away from those voices. They might still be looking for him. He was utterly confused in his direction now. He could be going toward Turibek, or toward K'Mari Range ... or out into the vast wilderness to the south. One of those dark storms was sweeping up, and Deimos was hidden. Soon the sharp sand began to pelt him.

Ketrik turned up his collar and ploughed on. He remembered that those storms usually, but not always, came up from the south. He guided his direction by that, and plunged on.

"At least one thing's settled," he muttered after a while. "I'm relieved of the problem of hiding my ship!"