Ragged patches of light floated past David Starr. Slowly he became aware of a tremendous tingling all about him and a separate pressure on his back. The back pressure resolved itself into the fact that he was lying face up on a hard mattress. The tingling he knew to be the aftermath of a stun-gun, a weapon whose radiation worked upon the nerve centers at the base of the brain.

Before light became coherent, before he was thoroughly aware of his surroundings, he felt his shoulders being shaken and the distant sting of sharp slaps on his cheeks. The light washed into his open eyes and he brought his tingling arm up to ward off the next slap.

It was Bigman leaning over him, his little rabbity face with its round snub nose nearly touching his. He said, "By Ganymede, I thought they finished you for good." '

David brought himself up to an aching elbow. He said, "It almost feels as if they did. Where are we?"

"In the farm lockup. It's no use trying to get out, either. The door's locked; the windows are barred." He looked depressed.

David felt under his arms. They had removed Ms blasters. Naturally! So much was to be expected. He said, "Did they stun you, too, Bigman?"

Bigman shook his head. "Zukis horizontaled me with the gun butt." He fingered a region of his skull with gingerly distaste. Then he swelled, "But I nearly broke his arm first."

There was the sound of footsteps outside the door. David sat up and waited. Hermes entered, and with him there came an older man, with a long, tired-looking face set off by faded blue eyes under bushy gray eyebrows that seemed fixed in a permanent furrow. He was dressed in city costume, which was much like that of Earth. He even lacked the Martian hip boots.

Hennes spoke to Bigman first. "Get out to the chowhouse and the first time you sneeze without permission you'll be broken in two."

Bigman scowled, waved to David with an "I'll be seeing you, Earthman," and swaggered out with a clattering of boots.

Hennes watched him leave and locked the door behind him. He turned to the man with the gray eyebrows. "This is the one, Mr. Makian. He calls himself Williams."

"You took a chance stunning him, Hennes. If you had killed him, a valuable lead might have gone with the canal-dust."

Hennes shrugged. "He was armed. We could take no chances. In any case, he's here, sir."

They were discussing him, David thought, as though he weren't there or were just another inanimate part of the bed.

Makian turned to him, his eyes hard. "You, there, I own this ranch. Over a hundred miles in any direction is all Makian. I say who is to be free and who is to be in prison; who works and who starves; even who lives and who dies. Do you understand me?"

"Yes," said David.

"Then answer frankly, and you'll have nothing to fear. Try to hide anything and we'll have it out of you one way or another. We may have to kill you. Do you still understand me?"

"Perfectly."

"Is your name Williams?"

"It's the only name I will give on Mars."

"Fair enough. What do you know about food poisoning?"

David swung his feet off the bed. He said, "Look, my sister died over an afternoon snack of bread and jam. She was twelve years old, and lay there dead with the jam still on her face. We called the doctor. He said it was food poisoning and told us not to eat anything in the house till he came back with certain analytical equipment. He never came back.

"Somebody else came instead. Someone with a great deal of authority. He had plain-clothes men to escort him. He had us describe all that had happened. He said to us, 'It was a heart attack.' We told him that was ridiculous because my sister had nothing wrong with her heart, but he wouldn't listen to us. He told us that if we spread ridiculous stories about food poisoning, we would get in trouble. Then he took the jar of jam with him. He was even angry with us for having wiped the jam from my sister's lips.

"I tried to get in touch with our doctor, but his nurse would never admit he was in. I broke into his office and found Mm there, but all he would say was that he had made a mistaken diagnosis. He seemed afraid to talk about it. I went to the police, but they wouldn't listen.

"The jar of jam the men took away was the only thing in the house my sister ate that day that the rest of the, family hadn't eaten as well. That jar was freshly opened and it was imported from Mars. We're old-fashioned people and like the old food. That was the only Mars product in the house. I tried to find out through the newspapers whether there had been any other cases of food poisoning. It all seemed so suspicious to me. I even went to International City. I quit my job and decided that in one way or another I would find out what had killed my sister and try to nail anyone that might be responsible. Everywhere I hit a blank, and then there came policemen with a warrant for my arrest.

"I was almost expecting that, and got out a step ahead of them. I came to Mars for two reasons. First, it was the only way to keep out of jail (though it doesn't seem so now, does it?), and second, because of one thing I did find out. There were two or three suspicious deaths in the restaurants of International City and in each case they were at restaurants which featured Martian cuisines. So I decided the answer was on Mars."

Makian was running a thick thumb down the long line of his chin. He said, "The yarn hangs together, Hennes. What do you think?"

"I say, get names and dates, and check the story. We don't know who this man is."

Makian sounded almost querulous. "You know we can't do that, Hennes. I don't want to do anything that would spread news of all this mess. It would break the entire Syndicate." He turned to David. "I'm going to send Benson to speak to you; he's our agronomist." Then, again to Hennes, "You stay here till Benson comes."

It was about half an hour before Benson came. During that interval David leaned carelessly back on the cot paying no attention to Hennes, who, for his part, played the same sort of game.

Then the door opened and a voice said, "I'm Benson." It was a gentle, hesitant voice and it belonged to a round-faced individual of about forty, with thinning sandy hair and rimless eyeglasses. His small mouth spread itself in a smile.

Benson went on, "And you, I suppose, are Williams?"

"That's right," said David Starr.

Benson looked carefully at the young Earthman, as though he were analyzing him by eye. He said, "Are you disposed to violence?"

"I'm unarmed," David pointed out, "and surrounded by a farm full of men quite ready to kill me if I step out of line."

"Quite right. Would you leave us, Hennes?"

Hennes jumped to his feet in protest. "That's not safe, Benson."

"Please, Hennes." Benson's mild eyes peered over his spectacles.

Hennes growled, clapped one hand against a boot in disgruntlement, and walked out the door. Benson locked it behind him.

"You see, Williams," he said apologetically, "in the last half-year I've grown to be an important man here. Even Hennes listens to me. I'm still not used to it." He smiled again. "Tell me. Mr. Makian says you actually witnessed a death by this strange food poisoning."

"My sister's."

"Oh!" Benson flushed. "I'm dreadfully sorry. I know it must be a painful subject to you, but might I have the details? It's very important."

David repeated the story he had earlier told Makian.

Benson said, "And it happened as quickly as that."

"It could only have been five to ten minutes after she had eaten."

"Terrible. Terrible. You have no idea how distressing all this is." He was rubbing his hands together nervously. "In any case, Williams, I'd like to fill in the story for you. You've guessed most of it, anyway, and, somehow, I feel responsible to you for what happened to your sister. All of us here on Mars are responsible until such time as we clear up the mystery. You see, this has been going on for months now, these poisonings. Not many, but enough to have us at our wit's end.

"We've traced back the poisoned foodstuffs and we are certain they come from no one farm. But one thing did turn up: all the poisoned food is shipped out of Wingrad City; the other two cities on Mars are clean so far. That would seem to indicate that the source of infection is within the city, and Hennes has been working on the assumption. He has taken to riding to the city, nights, on detective expeditions of Ms own, but he has turned up nothing."

"I see. That explains Bigman's remarks," said David.

"Eh?" Benson's face twisted in puzzlement, then cleared. "Oh, you mean the little fellow who goes about shouting all the time. Yes, he caught Hennes leaving once, and Hennes had him thrown out. Hennes is a most impulsive man. In any case, I think Hennes is wrong. Naturally all the poison would travel through Wingrad City. It is the shipping point for the entire hemisphere.

"Now Mr. Makian himself believes the infection to be deliberately spread through human agency. At least he and several others of the Syndicate have received messages offering to buy their farms for a ridiculously small sum. There is no mention of the poisoning and no evidence whatsoever of any connection between the offers to buy and this horrible business."

David was listening intently. He said, "And who makes these offers to buy?"

"Why, how should we know? I have seen the letters and they only say that if the offers are accepted, the Syndicate is to broadcast a coded message over a particular sub-etheric waveband. The price offer, the letters say, will decrease by 10 per cent each month."

"And the letters can't be traced?"

"I'm afraid not. They pass through the ordinary mails with an 'Asteroid' postmark. How can one search the Asteroids?"

"Have the Planetary Police been informed?"

Benson laughed softly. "Do you think Mr. Makian, or any of the Syndicate for that matter, would call in the police for a thing like this? This is a declaration of personal war to them. You don't properly appreciate the Martian mentality, Mr. Williams. You don't run to the law when you're in trouble unless you're willing to confess it's something you can't handle yourself. No farmboy is ever willing to do that. I've suggested that the information be submitted to the Council of Science, but Mr. Makian wouldn't even do that. He said the Council was working on the poisoning without success, and if that were the kind of darned fools they were, he would do without them. And that's where I come in."

"You're working on the poisoning too?" "That's right. I'm the agronomist here." "That's the title Mr. Makian gave you." "Uh-huh. Strictly speaking, an agronomist is a person who specializes in scientific agriculture. I've been trained in principles of fertility maintenance, crop rotation, and matters of that sort. I've always specialized in Martian problems. There aren't many of us and so one can get a rather good position, even though the farmboys sometimes lose patience with us and think we're just college idiots without practical experience. Anyway, I've had additional training as well in botany and bacteriology, so I've been put in charge by Mr. Makian of the entire research program on Mars with respect to the poisoning. The other members of the Syndicate are co-operating." "And what have you found out, Mr. Benson?" "Actually as little as the Council of Science, which is not surprising considering how little I have in the way of equipment and help in comparison with them. But I have developed certain theories. The poisoning is too rapid for anything but a bacterial toxin. At least if we consider the nerve degeneration that takes place and the other symptoms. I suspect Martian bacteria."

"What!"

"There is Martian life, you know. When Earthmen first arrived, Mars was covered with simple forms of life. There were giant algae whose blue-green color was seen telescopically even before space-travel was invented. There were bacteria-like forms that lived on the algae and even little insect-like creatures that were free-moving, yet manufactured their own food like plants."

"Do they still exist?"

"Why, certainly. We clear them off the land completely before converting areas to our own farms and introduce our own strains of bacteria, the ones that are necessary to plant growth. Out in the uncultivated areas, however, Martian life still flourishes."

"But how can they be affecting our plants, then.''

"That's a good question. You see, Martian farms are not like the Earth farm lands you're used to. On Mars, the farms are not open to sun and air. The sun on Mars doesn't give enough heat for Earth plants and there is no rain. But there is good, fertile soil and there is quite enough carbon dioxide which the plants live on primarily. So crops on Mars are grown under vast sheets of glass. They are seeded, cared for, and harvested by nearly automatic machinery so that our farmboys are machinists more than anything else. The farms are artificially watered by a system of planet-wide piping that carries back to the polar icecaps.

"I tell you this so you will realize that it would be difficult to infect plants ordinarily. The fields are closed and guarded from all directions except from beneath."

"What does that mean?" asked David.

"It means that underneath are the famous Martian caverns and within them there may be intelligent Martians."

"You mean Martian men?"

"Not men. But organisms as intelligent as man. I have reason to believe that there are Martian intelligences that are probably anxious to drive us intruding Earthmen from the face of their planet!"