"Most unusual," the General said, his tone betraying his opinion of the usefulness of teaching women to read. "You were saying..."

"Oh, yes, the First Dark Ages! They were a time in history with parallels to our own situation.

Then, as now, the world was a collection of warring fiefdoms, with no nation strong enough to enforce its will on its neighbors. The result -- as now -- was a growth of feudalism and a certain lack of stability.

Yet, the human race continued its technological advance right through the Middle Ages. Those years saw the invention of the horse collar, the stirrup, the lateen sail, and the first truly efficient plow -- all significant advances over Roman technology."

The dinner conversation continued for more than an hour. Beckwith had hoped that the wide-ranging discussion he had started would cause one of the Sonorans to slip and make a remark that would be a clue to their purpose here. No such luck. The conversation had never risen above the level of a polite debate comparing the present with the "good old days."

Eventually, Beckwith concluded that most of his dinner mates really didn't know what was going on -- not surprising if the powers-that-be back home were right in their suspicions. So, just when theconversation was beginning to lag, he reached into his repertoire of anecdotes and told a funny story.

One advantage of the current state of world communications was that jokes did not age as quickly as they once had. He had his listeners chuckling in a matter of moments.

The great crackling log in the fireplace had burned low when he finally asked to be excused and started toward the rear of the hacienda. His demeanor showed no sign of the adrenaline storm that raged in his bloodstream. For if his probing had stirred the General to suspect that he was more than the traveling medic/storyteller/troubadour he pretended to be, this was the moment of greatest danger.

No lurking guards stepped out to bar his way, no shots rang out of the darkness, not even the hacienda dogs bothered him as he crunched along the graveled pathway at the rear of the house. He quickly finished taking care of necessities in the hacienda outhouse, and stepped back into the cold night air of the desert.

He paused to light his pipe. The lighter was a flare of blue against the yellow lights emanating from the hacienda windows. He puffed quickly, and was rewarded with the bitter taste of tobacco smoke on his tongue. He drew in a lung full of the smoke, and then exhaled slowly. As he did so, a bright light just above the northern horizon caught his attention. He stepped out of the shade of the trees to get a clear view as the familiar star began to climb the sky.

Beckwith's internal alarm clock woke him two hours before dawn to a pitch-black world lit only by star shine. In spite of the heat of the previous day, the night air was brisk against his bare skin, causing him to shiver at the thought of throwing back the covers and leaving the warmth of his soft bed. He stalled the inevitable for a few moments by remembering the bright star he had watched cross the heavens the previous evening.

By rights, the Catastrophe should have ended all life on Earth. That it had not was a tribute to the overlapping layers of orbital fortresses and satellites the two pre-Catastrophe superpowers had built with such laborious care over a thirty-year period. When finally the world had gone insane and the missiles began to fly, fewer than one in fifty warheads survived to explode against their intended targets. The other forty-nine had either been destroyed with their carrier missiles, in transit through the vacuum of s.p.a.ce, or in the final seconds of their terminal maneuvers.

Coordinating the defenses had been the great manned battle stations. The greatest of these was High Citadel , the prime command-and-control facility for the western alliance. First constructed in the early years of the twenty-first century,High Citadel had been constantly enlarged, strengthened, and improved. In addition to being the nerve center for all western orbital defenses,High Citadel 's computers had been used to archive all manner of scientific and technological data.

During the six weeks the war lasted,High Citadel had defeated everything the eastern bloc could throw against it. It had destroyed the east's own system of orbital fortresses in a duel that had turned night into day across the entire face of the planet. Finally, it had directed the strikes that destroyed the eastern bloc's surviving missile fields, and thereby brought about a cessation of hostilities.

The end came too late to save technological civilization. For, although the orbiting satellites and defense stations had saved the human race from extinction, sufficient megatonnage had gotten through to smash the industrial base on which civilization was built. In less than a year, Earth was swept by successive waves of famine and plague. Those men and women still in orbit watched as their world disintegrated into ever-smaller warring groups. These orbiting warriors were finally forced to abandon their posts as food, water, and air ran low. One by one, their emergency craft departedHigh Citadel toslip below the roiling clouds of Earth, never to return. For eighty years, the deserted battle station's anti-laser armor had reflected the rays of the sun with mirror brightness, makingHigh Citadel one of the brightest stars in the terrestrial sky.

The sound of a distant catfight brought Beckwith back to the problem at hand. Unable to postpone it any longer, he slipped out of bed and groped in darkness for his leather case. His fingers quickly found the hidden catches that freed the false bottom from the valise. He withdrew a garment from the secret compartment. What little radiance fell through his open window was sufficient to show the darksuit to be a pool of deeper black against the near stygian dark around him.

Beckwith carefully climbed inside, zipping the light amplifier hood over his face as a last step. He was now encased in shadow, able to see, but not be seen.

He turned back to the case, working more quickly now that the world was lit in a bright, greenish glow. The hidden compartment yielded up a holster and needle gun that he belted around his middle.

Two small rectangles the size of dominoes went into his breast pocket. He visually inventoried the half dozen tiny vials in the bottom of the case, checking them for any telltale signs of breakage before carefully resealing the hidden compartment. The floorboards creaked slightly as he moved to the open window.

There were two guards roaming more or less at random through the courtyard below. Both were fairly distant from the hacienda and Beckwith took advantage of this good fortune to lever himself up onto the tiled roof of the hacienda. Once there, he catfoooted his way to the far side of the building, the side closest to the Sonoran bivouac. After a moment's hesitation at the edge of the roof, he concluded that his best avenue of approach was atop the village wall. Better to be silhouetted against the black sky than the whitewashed walls of the town -- a.s.suming that he did not break his neck in the process.

He thanked the G.o.ds of Fission that this village was too poor to top their wall with metal spikes or barbed wire as he moved in a balancing actc.u.m hundred-meter dash along the narrow, impromptu footpath. In a matter of seconds, he found himself overlooking a small sea of tents.

The Sonoran encampment was a st.u.r.dy little fortress with an air of permanence about it. On one side, the conquerors had used the village wall -- the same wall where Beckwith now squatted.

Everywhere else, they were building new walls from native rock cemented together with adobe. By the progress they had already made, Beckwith judged their annexation of Nuevo Tubac would be complete within another month.

The thought left a sour taste in his mouth. He liked Ynicente Galway and the people of this village.

It would be a tragedy to see them fall under Juan Pablo's iron heel. The real tragedy, of course, would be losing Esperanza Galway. He had watched that precocious little girl for nearly ten years now with an interest far from avuncular. The Public Health Service's greatest need was for good people and Darol Beckwith had planned to recruit Espe Galway for the training academy on his next visit. Now there was a good chance that would never happen. Keeping this one pueblo out of Sonoran hands was not his concern at the moment. Nor was securing Espe for the service. His current mission went far beyond the mere delivery of a few hundred likable people from the bonds of slavery.

Beckwith slid down from the wall, chiding himself for the nasty tendency towards morose thoughts he had developed lately. Then he hadn't time for such thoughts as he padded quietly between rows of tents, slowly making his way toward two large machines parked at the center of the encampment. A tall antenna mast rose between them.

He hid among the tents, acutely conscious of the snores around him, and gauged the moment when the two guards pacing in front of the silent machines would be at the farthest reaches of their circuits. Then it was a swift, crouching run through a dark gap between watch fires, and a rolling dive into the shadows beyond.

The steam wagons were nothing like the pictures of the ancients' sleek machines he had seen. They were both large flatbeds, with their alcohol-powered engines mounted toward the back near the drilling fixtures. The whole of the wagon bodies in front of the main tiller was covered with canvas. Beckwith pulled himself aboard one, being careful not to dislodge the loose equipment scattered haphazardly around the floorboards. Once inside, even his light amplifiers were of limited use as he found himself groping in murky surroundings.

His first stop was at the ancient radio set that was perched on a built-in shelf on one side of the steamer. As expected, the radio was a pre-Catastrophe model, its black plastic case cracked and its battery pack trailing an unsightly cl.u.s.ter of wires. Beckwith removed a screwdriver from his pocket and quickly opened the back of the transmitter to reveal the integrated circuitry inside. He removed one of the dominoes from his pocket and wedged it into the radio's power supply. He then hurriedly replaced the back of the case.

Sometime tomorrow, after the radio had worked for several hours, there would be a quick crackling noise and a puff of smoke from inside the circuit enclosure. When the Sonoran operators opened the case, they would find fused and twisted circuitry, the apparent victim of a ma.s.sive short circuit. With any luck, they would mark the failure as one of old age. Whether they did so or not, however, it was vital to the success of Beckwith's mission that contact between the Mexican expeditionary force and their emperor be severed.

After replacing the radio on its shelf, Beckwith quickly searched the steamer for spare transmitter parts. He poked into various boxes with the beam of a tiny flashlamp, cataloging items by sight and feel as he went. He quickly found the metal detectors and radiation counters of which Espe had spoken. He also found what appeared to be a jury-rigged seismograph from pre-Catastrophe days in one corner.

Next to it lay a pile of recordings. Apparently, someone was very interested in the geological formations in this area. Maybe the Sonorans were prospecting for oil!

He considered the possibility. True, the ancients had pretty well drained the planet of the legendary stuff, but who knew? There might still be a pool or two around for the taking.

He photographed everything and slipped outside, intending to give the other steam wagon a thorough going over. He changed his plans as he caught sight of the burgeoning glow on the eastern horizon. It would be light enough for naked eye seeing in another half-hour, and by that time, he planned to be safely back in his room.

"All right, Espe, what istinea ?"

"Tinea refers to a group of common fungus infections, Dr. Darol; also known as ringworm. The fungi involved areMicrospora ,Trichophyton , and ... uh, ...Epidermophyton . Tinea capitis is ringworm of the scalp;tinea cruris , of the crotch;tinea pedis , of the feet."

"And how does one treat these very itchy problems, Espe?"

"By direct application of any one of several anti-fungal agents, including..."

Beckwith smiled. "Never mind. I should have known that you would keep up with your studies.

You'll make a fine doctor someday.""Do you really think so, Dr. Darol?"

"I would not have said it if I didn't," he replied gruffly. "Now go get me a bucket of hot water so we can get this place cleaned up."

Beckwith and Espe Galway had spent the morning preparing one room of Nuevo Tubac's small church for the traveling doctor's use. One of Ynicente Galway's large mahogany tables had been moved there from the hacienda, and draped in cloth that had been boiled in disinfectant. A similar cloth covered another table on top of which several of Beckwith's instruments were neatly arranged. Battered instrument cases marked with a caduceus were piled in a corner. On their covers were stenciled the words:

PUBLIC HEALTH SERVICE.

In Service to Humanity.

Beckwith and Espe had worked through the morning and were ready to begin the sterilization process as time for the noon meal approached. It was the third year that Espe had acted as Beckwith's nurse, and she went about the preliminaries with the practiced touch of a veteran. As Espe left the church to retrieve an iron kettle filled with steaming water, Captain Villela entered the examination room and gazed around in interest.

"Good morning, Doctor Beckwith," the Captain of Ordnance said. "The general sent me over to see how you are getting along. I trust you have all that you need."

"Thank you, yes," Beckwith replied. "We're about to disinfect the examination room."

"So I see. I am surprised that you go to the trouble of individual diagnoses. I always thought that you public health people were interested in water supplies and hygiene, and left the actual laying on of hands to others."

Beckwith shrugged. "We circuit doctors tend to be jacks of all trade, Capitan. And while our primary duty is to insure the health of a community through public hygiene, we also dabble in individual cures."

At that moment, Espe returned with a kettle full of boiling water from the fire where Beckwith had sterilized his instruments.

"Will that be all, Captain Villela?" Beckwith asked as he prepared the water by measuring out a few drops of disinfectant into the kettle.

"Yes, Doctor. Let me know if you need anything."

"Thank you, I will."

Beckwith watched the officer stride out into the bright sunshine before turning to Espe. "Shall we begin scrubbing?"

After twenty minutes of hard labor, Beckwith called a halt. The two of them sprawled on the floor and examined their handiwork.Espe looked at Beckwith, her black eyes regarding him seriously, and said, "Doctor Darol."

"Yes, Espe?"

"I've been meaning to talk to you about Manuel Vargas."

"What about him?"

She leaned close and lowered her voice to a whisper. "Sometimes when he would get drunk, Old Manuel would say things."

"What sort of things?"

"He would hint that you and he were the only two who knew a great secret."

"Oh?" Beckwith asked, his eyebrows rising in inquiry.

"He would never tell anyone anything, you understand. He would just keep muttering that you were the only one who appreciated him. I didn't think anything of it until they caught him with that radio."

"You said yesterday that it might have been a radio. Now you're sure?"

She nodded. "The fat Generalissimo had it on my father's desk, looking at it, when I took him his lunch one day. It was a radio all right, although unlike any I have ever seen. There was a black box with LED's on its face and a keypad. It was attached by a coiled cord to something that looked like an umbrella frame with a pistol grip."

"Sounds like some sort of communications gear," Beckwith said, nodding, "but why do you think I know anything about it?"

"My room is across the hall from yours."

"So?"

"This morning I heard you moving about before dawn. I figured to tell you about Manuel Vargas then, so I tiptoed across the hall to your room. I knocked twice before opening the door. You weren't there."

"Maybe I went down to the outhouse."

Espe shook her head. "I would have heard you on the stairs."

"So, if I wasn't in my room, where was I?"

"I think you were spying on the Sonorans."

"And if I was?"

"Then I want to help you."

Beckwith did not answer for a full minute. Finally, he said, "Perhaps youcan help. I would like to look over the Sonoran excavation. I need a way to slip out of the village without being seen. Have any ideas?"

She grinned and was again a little girl. "I will come to your room after dinner and show you the way."# "Watch your head."

Espe's warning echoed hollowly from the walls of the small tunnel through which they crawled on their hands and knees. Beckwith glanced up at the sound, wondering how much further they would have to travel in this cramped style. Espe was a black silhouette framed in the dim light of the flash she carried.

The two of them had spent the day treating the people of the village. Night had begun to fall when they finished with their last patient and returned to the hacienda. At dinner, General Trujillo had seemed distracted, as though his mind were on something more important than making conversation with his guests. Beckwith told another of his stories and swapped lies with some of the Sonoran officers before going upstairs to bed. An hour later, Espe had knocked softly on his door and the two of them had slipped down into Ynicente Galway's wine cellar. There Espe had shown him the entrance to an escape tunnel concealed behind one of the wine casks.

They had crawled some two hundred meters, and Beckwith was about to ask Espe how much farther it would be, when a round metal hatch appeared at the end of his restricted field of view. In another few seconds, he found himself half crawling/half dragged out into the frigid night air. It was still an hour or so before midnight and a quarter moon hovered in the sky overhead, casting a soft silver glow across the landscape.

Beckwith glanced back at the tunnel entrance. The escape hole was well camouflaged. If it had not been standing agape, it would have been invisible. He doubted that he could have spotted it in broad daylight, even had he known where to look. Espe did something to a section of the rock wall through which they had emerged and the camouflaged opening swung shut on well-oiled hinges.

"Which way?" he asked.

She pointed a direction and they started off, keeping to the cover of the arroyo into which they had emerged. Both were dressed head to toe in black, although not in darksuits. Since Espe had none such, the protection offered by Beckwith's darksuit would have been useless.

Espe led him across the desert and up a rise that Beckwith knew from previous visits was actually the rim of a broad depression in the midst of rolling hills. They carefully worked their way to the crest of the rise, moving the last hundred meters on their bellies. When they reached the top and were able to look into the bowl-shaped valley beyond, they found a large detachment of men working around a wooden derrick. The derrick covered a vertical shaft that had been sunk into the dry desert soil. The scene was lit by numerous lanterns strung between rough-hewn poles. A steam engine puffed away beside a ramshackle building, emitting a column of black smoke into the moonlit sky. As they watched, a lift platform surfaced in the midst of the st.u.r.dy looking derrick and was immediately manhandled to solid ground.

"Recognize anyone?" Beckwith asked Espe, relying on her younger eyes to subst.i.tute for the binoculars the Sonorans had confiscated.

Espe rose up on her elbows and squinted at the activity for a few moments. "There is Capitan Rodriguez talking to a soldier. And over there..." she gestured to the shaft. "... is aCoronel of Inginieros who has been absent from dinner for the last three nights. The man he is talking to, the one with his back to us, is General Trujillo, I think."

"I want to get closer," Beckwith said. "You stay here."He picked a tentative route that would take him close to the excavation. The floor of the small valley was covered with mesquite bushes and a few scrubby Palo Verde trees. Even without his amplifier hood, he could see well enough by moonlight to spot the sentries posted around the rim. There seemed to be quite a few of them. They would make any approach difficult, but the ground cover was such that if he were careful, he should be able to get into position without being spotted.

"There is an old drainage ditch of the ancients a hundred meters from here, Doctor Darol. I will show you." Espe did not wait for an answer, but moved forward with a catlike speed that Beckwith knew he would be hard put to match silently.

The drainage ditch was a concrete lined culvert that had been stained and broken by age until it was open to the sky. Beckwith studied the workmanship. There was no mistaking the product of the pre-Catastrophe machine culture.

"Why didn't anyone ever tell me about this, Espe?"

She looked at the jutting, broken concrete and shrugged. "You never asked, Doctor Darol. Father says that this ditch paralleled an old railroad spur before someone ripped up the tracks."

"A railroad? Here? The maps don't show any railroad."

"Maybe father was mistaken."

"Where does this lead?" Beckwith asked, gesturing along the length of the ditch.

"Almost to the Sonoran diggings. We should be able to see everything from the other end. Just be sure to stay down."

This time Beckwith took the lead after debating whether he should send Espe back to the pueblo.