“Petroleum — of course!” Jason enthused out loud, then bent his attentions to pushing when the overseer gave him an ugly look and cracked his whip menacingly.

This was the secret of the D’zertanoj, and the source of their power. Mountains were visible nearby, and hills, towering above the surrounding walls. The captured slaves had been drugged so they would not even know in which direction they had been brought to this hidden site, or how long the trip was. Here in this guarded valley they labored to pump the crude oil that their masters used to power their big desert wagons. Or did they use crude oil for this? The petroleum was gurgling out in a solid stream now, and running down an open trough that vanished through the wall into the same building as the turning belts. And what barbaric devilishness went on in there? A thick chimney crowned the building and produced clouds of black smoke, while from the various openings in the wall came a tremendous stench that threatened to lift the top off his head.

At the same moment that he realized what was going on in the building a guarded door was opened and Edipon came out, blowing his sizable nose in a scrap of rag. The creaking wheel turned and when its rotation brought Jason around again he called out to him.

“Hey, Edipon, come over here. I want to talk to you. I’m the former Ch’aka, in case you don’t recognize me out of uniform.”

Edipon gave him one look, then turned away dabbing at his nose. It was obvious that slaves held no interest for him, no matter what their position had been before their fall. The slave-driver ran over with a roar, raising his whip, while the slow rotation of the wheel carried Jason away. He shouted back over his shoulder.

“Listen to me — I know a lot and can help you.” Only a turned back for an answer and the whip was already whistling down. It was time for the hard sell. “You had better hear me — because I know that what comes out first is best. Yeow!” This last was involuntary as the whip landed.

Jason’s words were without meaning to the slaves as well as the overseer who was raising his whip for another blow, but their impact on Edipon was as dramatic as if he had stepped on a hot coal. He shuddered to a halt and wheeled about, and even at this distance Jason could see that a sickly gray tone had replaced his normal browned color of his skin.

“Stop the wheel!” he shouted.

***

This unexpected command drew the startled attention of everyone. The gape-mouthed overseer lowered his whip while the slaves stumbled and halted and the wheel groaned to a stop. In the sudden silence Edipon’s steps echoed loudly as he ran to Jason, halting a hand’s breadth away, his lips drawn back from his teeth with tension as if he were prepared to bite.

“What was that you said?” He hurled the words at Jason while his fingers half-plucked a knife from his belt.

Jason smiled, looking and acting calmer than he felt. His barb had gone home, but unless he proceeded carefully so would Edipon’s knife — into his stomach. This was obviously a very sensitive topic.

“You heard what I said — and I don’t think you want me to repeat it in front of all these strangers. I know what happens here because I come from a place far away where we do this kind of thing all the time. I can help you. I can show you how to get more of the best, and how to make your caroj work better. Just try me. Only unchain me from this bar first and let’s get to some place private where we can have a nice chat.”

Edipon’s thoughts were obvious. He chewed his lip and looked hotly at Jason, fingering the edge of his knife. Jason only returned a smile of pure innocence and tapped his fingers happily on the bar, just marking time while he waited to be released. Yet in spite of the cold there was a rivulet of sweat trickling down his spine. He was gambling everything on Edipon’s intelligence, that the man’s curiosity would overcome the immediate desire to silence the slave who knew so much about things so secret, hoping that he would remember that slaves could always be killed, and that it wouldn’t hurt to ask a few questions first. Curiosity won and the knife dropped back into the sheath while Jason let his breath out in a relieved sigh. It had been entirely too close, even for a professional gambler; his own life on the board was a little higher stakes than he enjoyed playing for.

“Release him from the bar and bring him to me,” Edipon ordered, then strode agitatedly away. The other slaves watched wide-eyed as the blacksmith was rushed out, and with much confusion and shouted orders Jason’s chain was cut from the bar where it joined the heavy staple.

“What are you doing?” Mikah asked, and one of the guards backhanded him to the ground. Jason just smiled and touched his finger to his lips as his chain was released and they led him away. He was free from bondage and he would stay that way if he could convince Edipon that he would be better off in some capacity other than dumb labor.

***

The room they led him to contained the first touches of decoration or self-indulgence that he had seen on this planet. The furniture was carefully constructed, with an occasional bit of carving to brighten it, and there was a woven cover on the bed. Edipon stood by a table, tapping his fingers nervously on the dark polished surface. “Lock him up,” he ordered the guards, and Jason was secured to a sturdy ringbolt that projected from the wall. As soon as the guards were gone he stood before Jason and drew his knife. “Tell me what you know or I will kill you at once.”

“My past is an open book to you, Edipon. I come from a land where we know all the secrets of nature — ”

“What is the name of this land? Are you a spy from Appsala?”

“I couldn’t very well be one since I have never heard of the place.” Jason pulled at his lower lip, wondering just how intelligent Edipon was, and just how frank he could be with him. This was no time to get tangled up in lies about planetary geography: it might be best to try him on a small dose of the truth. “If I told you I came from another planet, another world in the sky up among the stars, would you believe me?”

“Perhaps. There are many old legends that our forefathers came from a world beyond the sky, but I have always dismissed this as religious drivel, fit only for women.”

“In this case the girls happen to be right. Your planet was settled by men whose ships crossed the emptiness of space as your caroj pass over the desert. Your people have forgotten about that and lost the science and knowledge you once had, but in other worlds the knowledge is still held.”

“Madness!”

“Not at all, it is science, though many times confused as being the same thing. I’ll prove my point. You know that I could never have been inside your mysterious building out there, and I imagine you can be sure no one has told me its secrets. Yet I’ll bet you that I can describe fairly accurately what is in there — not from seeing the machinery, but from knowing what must be done to oil in order to get the products you need. Do you want to hear?”

“Proceed,” Edipon said, sitting on a corner of the table and balancing the knife loosely in his palm.

“I don’t know what you call it, the device, but in the trade it is a pot still used for fractional distillation. Your crude oil runs into a tank of some kind, and you pipe it from there to a retort, some big vessel that you can seal airtight. Once it is closed you light a fire under the thing and try to get all the oil to an even temperature. A gas rises from the oil and you take it off through a pipe and run it through a condenser, probably more pipe with water running over it. Then you put a bucket under the open end of the pipe and out of it drips the juice that you burn in your caroj to make them move.”