It was night when Feldman came to, and the temperature was dropping rapidly. He struggled to sit up through a fog of pain. Somewhere in his bag, he should have an anodyne tablet that would kill any ache. He finally found the pill and swallowed it, fumbling with the aspirator lip opening.

The aspirator meant life to him now, he suddenly realized. He twisted to stare at the tiny charge-indicator for the battery. It showed half-charge. Then he saw that someone had attached another battery beside it. He puzzled briefly over it, but his immediate concern was for shelter.

Apparently he was still where he had been knocked out. There was a light coming from the little station, and he headed toward that, fumbling for the few quarters that represented his entire fortune.

Maybe it would have been better if the tubemen had killed him. Batteries were an absolute necessity here, food and shelter would be expensive, and he had no skills to earn his way. At most, he had only a day or so left. But meantime, he had to find warmth before the cold killed him.

The tiny restaurant in the station was still open, and the air was warm inside. He pulled off the aspirator, shutting off the battery.

The counterman didn't even glance up as he entered. Feldman gazed at the printed menu and flinched.

"Soup," he ordered. It was the cheapest item he could find.

The counterman stared at him, obviously spotting his Earth origin. "You adjusted to synthetics?"

Feldman nodded. Earth operated on a mixed diet, with synthetics for all who couldn't afford the natural foods there. But Mars was all synthetic. Many of the chemicals in food could exist in either of two forms, or isomers; they were chemically alike, but differently crystallized. Sometimes either form was digestible, but frequently the body could use only the isomer to which it was adjusted.

Martian plants produced different isomers from those on Earth. Since the synthetic foods turned out to be Mars-normal, that was probably the more natural form. Research designed to let the early colonists live off native food here had turned up an enzyme that enabled the body to handle either isomer. In a few weeks of eating Martian or synthetic food, the body adapted; without more enzyme, it lost its power to handle Earth-normal food.

The cheapness of synthetics and the discovery that many diseases common to Earth would not attack Mars-normal bodies led to the wide use of synthetics on Earth. No pariah could have been expected to afford Earth-normal.

Feldman finished the soup, and found a cigarette that was smokable. "Any objections if I sit in the waiting room?"

He'd expected a rejection, but the counterman only shrugged. The waiting room was almost dark and the air was chilly, but there was normal pressure. He found a bench and slumped onto it, lighting his cigarette. He'd miss the smokes—but probably not for long. He finished the cigarette reluctantly and sat huddled on the bench, waiting for morning.

The airlock opened later, and feet sounded on the boards of the waiting-room floor, but he didn't look up until a thin beam of light hit him. Then he sighed and nodded. The shoes, made of some odd fiber, didn't look like those of a cop, but this was Mars. He could see only a hulking shadow behind the light.

"You the man who was a medical doctor?" The voice was dry and old.

"Yeah," Feldman answered. "Once."

"Good. Thought that space crewman was just lying drunk at first. Come along, Doc."

"Why?" It didn't matter, but if they wanted him to move on, they'd have to push a little harder.

The light swung up to show the other. He was the shade of old leather with a bleached patch of sandy hair and the deepest gray eyes Feldman had ever seen. It was a face that could have belonged to a country storekeeper in New England, with the same hint of dry humor. The man was dressed in padded levis and a leather jacket of unguessable age. His aspirator seemed worn and patched, and one big hand fumbled with it.

"Because we're friends, Doc," the voice drawled at him. "Because you might as well come with us as sit here. Maybe we have a job for you."

Feldman shrugged and stood up. If the man was a Lobby policeman, he was different from the usual kind. Nothing could be worse than the present prospects.

They went out through the doors of the waiting room toward a rattletrap vehicle. It looked something like a cross between a schoolboy's jalopy and a scaled-down army tank of former times. The treads were caterpillar style, and the stubby body was completely enclosed. A tiny airlock stuck out from the rear.

Two men were inside, both bearded. The old man grinned at them. "Mark, Lou, meet Doc Feldman. Sit, Doc. I'm Jake Mullens, and you might say we were farmers."

The motor started with a wheeze. The tractor swung about and began heading away from Southport toward the desert dunes. It shook and rattled, but it seemed to make good time.

"I don't know anything about farming," Feldman protested.

Jake shrugged. "No, of course not. Couple of our friends heard about you where a spaceman was getting drunk and tipped us off. We know who you are. Here, try a bracky?"

Feldman took what seemed to be a cigarette and studied it doubtfully. It was coarse and fibrous inside, with a thin, hard shell that seemed to be a natural growth, as if it had been chopped from some vine. He lighted it, not knowing what to expect. Then he coughed as the bitter, rancid smoke burned at his throat. He started to throw it down, and hesitated. Jake was smoking one, and it had killed the craving for tobacco almost instantly.

"Some like 'em, most don't," Jake said. "They won't hurt you. Look—see that? Old Martian ruins. Built by some race a million years ago. Only half a dozen on Mars."

It was only a clump of weathered stone buildings in the light from the tractor, and Feldman had seen better in the stereo shots. It was interesting only because it connected with the legendary Martian race, like the canals that showed from space but could not be seen on the surface of the planet.

Feldman waited for the other to go on, but Jake was silent. Finally, he ground out the butt of the weed. "Okay, Jake. What do you want with me?"

"Consultation, maybe. Ever hear of herb doctors? I'm one of them."

Feldman knew that the Lobby permitted some leniency here, due to the scarcity of real medical help. There was only one decent hospital at Northport, on the opposite side of the planet.

Jake sighed and reached for another bracky weed. "Yeah, I'm pretty good with herbs. But I got a sick village on my hands and I can't handle it. We can't all mortgage our work to pay for a trip to Northport. Southport's all messed up while the new she-doctor gets her metabolism changed. Maybe the old guy there would have helped, but he died a couple months ago. So it looks like you're our only hope."

"Then you have no hope," Feldman told him sickly. "I'm a pariah, Jake. I can't do a thing for you."

"We heard about your argument with the Lobby. News reaches Mars. But these are mighty sick people, Doc."

Feldman shook his head. "Better take me back. I'm not allowed to practice medicine. The charge would be first-degree murder if anything happened."

Lou leaned forward. "Shall I talk to him, Jake?"

The old man grimaced. "Time enough. Let him see what we got first."

Sand howled against the windshield and the tractor bumped and surged along. Feldman took another of the weeds and tried to estimate their course. But he had no idea where they were when the tractor finally stopped. There was a village of small huts that seemed to be merely entrances to living quarters dug under the surface. They led him into one and through a tunnel into a large room filled with simple cots and the unhappy sounds of sick people.

Two women were disconsolately trying to attend to the half-dozen sick—four children and two adults. Their faces brightened as they saw Jake, then fell. "Eb and Tilda died," they reported.

Feldman looked at the two figures under the sheets and whistled. The same black specks he had seen on the face of Billings covered the skins of the two old people who had died.

"Funny," Jake said slowly. "They didn't quite act like the others and they sure died mighty fast. Darn it, I had it figured for that stuff in the book. Infantile paralysis. How about it, Doc? Sort of like a cold, stiff sore neck."

It was clearly polio—one of the diseases that could attack Mars-normal flesh. Feldman nodded at the symptoms, staring at the sick kids. He shrugged, finally. "There's a cure for it, but I don't have the serum. Neither do you, or you wouldn't have brought me here. I couldn't help if I wanted to."

"That old book didn't list a cure," Jake told him. "But it said the kids didn't have to be crippled. There was something about a Kenny treatment. Doc, does the stuff really cripple for life?"

Feldman saw one of the boys flinch. He dropped his eyes, remembering the Lobby's efficient spy service on Earth and wondering what it was like here. But he knew the outcome.

"Damn you, Jake!"

Jake chuckled. "Thought you would. We sure appreciate it. Just tell us what to do, Doc."

Feldman began writing down his requirements, trying to remember the details of the treatment. Exercise, hot compresses, massage. It was coming back to him. He'd have to do it himself, of course, to get the feel of it. He couldn't explain it well enough. But he couldn't turn his back on the kids, either.

"Maybe I can help," he said doubtfully as he moved toward a cot.

"No, Doc." Jake's voice wasn't amused any longer, and he held the younger man back. "You're doing us a favor, and I'll be darned if I'll let you stick your neck out too far. You can't treat 'em yourself. Mars is tougher than Earth. You should live under Space Lobby and Medical Lobby here a while. Oh, maybe they don't mind a few fools like me being herb doctors, but they'd sure hate to have a man who can do real medicine outside their hands. You let me do it, or get in the tractor and I'll have Lou drive you back. Once you start in here, there'll be no stopping. Believe me."

Feldman looked at him, seeing the colonials around him for the first time as people. It had been a long time since he'd been treated as a fellow human by anyone.

Jake was right, he knew. Once he put his hand to the bandage, eventually there'd be no turning back from the scalpel. These people needed medical help too desperately. Eventually, the news would spread, and the Lobby police would come for him. Chris couldn't afford to shield him. In fact, he was sure now that she'd hunt him night and day.

"Don't be a fool, Jake," he ordered brusquely. He handed his list to one of the women. "You'll have to learn to do what I do," he told the people there. "You'll have to work like fools for weeks. But there won't be many crippled children. I can promise that much!"

He blinked sharply at the sudden hope in their eyes. But his mind went on wondering how long it would be before the inevitable would catch up with him. With luck, maybe a few months. But he hadn't been blessed with any superabundance of luck. It would probably be less time than he thought.