Dal and Tiger crowded up to the screen. "What's the matter?" Tiger said.

"I don't see ... _wait a minute!_"

"Yes, you'd better look again," Jack said. "What do you think, Dal?"

"We'd better get down there fast," Dal said, "and see what's going on.

It looks to me like we've got a tiger by the tail...."

They climbed down the ladder once again, with the antibody flasks and sterile syringes strapped to their backs. But this time the greeting was different from before.

The Bruckian spokesman and the others who had not yet been inoculated drew back from them in terror as they stepped to the ground. Before, the people on the field had crowded in eagerly around the ship; now they were standing in silent groups staring at the doctors fearfully and muttering among themselves.

But the doctors could see only the inoculated people in the two roped-off areas. Off to the right among the infected Bruckians who had received the antibody there were no new dead--but there was no change for the better, either. The sick creatures drifted about aimlessly, milling like animals in a cage, their faces blank, their jaws slack, hands wandering foolishly. Not one of them had begun reacting normally, not one showed any sign of recognition or recovery.

But the real horror was on the other side of the field. Here were the healthy ones, the uninfected ones who had received preventative inoculations. A few hours before they had been left standing in quiet, happy groups, talking among themselves, laughing and joking....

But now they weren't talking any more. They stared across at the doctors with slack faces and dazed eyes, their feet shuffling aimlessly in the dust. All were alive, but only half-alive. The intelligence and alertness were gone from their faces; they were like the empty sh.e.l.ls of the creatures they had been a few hours before, indistinguishable from the infected creatures in the other compound.

Jack turned to the Bruckian spokesman in alarm. "What's happened here?"

he asked. "What's become of the ones we inoculated? Where have you taken them?"

The spokesman shrank back as though afraid Jack might reach out to touch him. "Taken them!" he cried. "We have moved none of them! Those are the ones you poisoned with your needles. What have you done to make them like this?"

"It--it must be some sort of temporary reaction to the injection," Jack faltered. "There was nothing that we used that could possibly have given them the disease, we only used a substance to help them fight it off."

The Bruckian was shaking his fist angrily. "It's no reaction, it is the plague itself! What kind of evil are you doing? You came here to help us, and instead you bring us more misery. Do we not have enough of that to please you?"

Swiftly the doctors began examining the patients in both enclosures, and on each side they found the same picture. One by one they checked the ones that had previously been untouched by the plague, and found only the sagging jaws and idiot stares.

"There's no sense examining every one," Tiger said finally. "They're all the same, every one."

"But this is impossible," Jack said, glancing apprehensively at the growing mob of angry Bruckians outside the stockades. "What could have happened? What have we done?"

"I don't know," Tiger said. "But whatever we've done has turned into a boomerang. We knew that the antibody might not work, and the disease might just go right ahead, but we didn't antic.i.p.ate anything like this."

"Maybe some foreign protein got into the batch," Dal said.

Tiger shook his head. "It wouldn't behave like _this_. And we were careful getting it ready. All we've done was inject an antibody against a specific virus. All it could have done was to kill the virus, but these people act as though they're infected now."

"But they're not dying," Dal said. "And the sick ones we injected stopped dying, too."

"So what do we do now?" Jack said.

"Get one of these that changed like this aboard ship and go over him with a fine-toothed comb. We've got to find out what's happened."

He led one of the stricken Bruckians by the hand like a mindless dummy across the field toward the little group where the spokesman and his party stood. The crowd on the field were moving in closer; an angry cry went up when Dal touched the sick creature.

"You'll have to keep this crowd under control," Dal said to the spokesman. "We're going to take this one aboard the ship and examine him to see what this reaction could be, but this mob is beginning to sound dangerous."

"They're afraid," the spokesman said. "They want to know what you've done to them, what this new curse is that you bring in your syringes."

"It's not a curse, but something has gone wrong. We need to learn what, in order to deal with it."

"The people are afraid and angry," the spokesman said. "I don't know how long I can control them."

And indeed, the att.i.tude of the crowd around the ship was very strange.

They were not just fearful; they were terrified. As the doctors walked back to the ship leading the stricken Bruckian behind them, the people shrank back with dreadful cries, holding up their hands as if to ward off some monstrous evil. Before, in the worst throes of the plague, there had been no sign of this kind of reaction. The people had seemed apathetic and miserable, resigned hopelessly to their fate, but now they were reacting in abject terror. It almost seemed that they were more afraid of these walking sh.e.l.ls of their former selves than they were of the disease itself.

But as the doctors started up the ladder toward the entrance lock the crowd surged in toward them with fists raised in anger. "We'd better get help, and fast," Jack said as he slammed the entrance lock closed behind them. "I don't like the looks of this a bit. Dal, we'd better see what we can learn from this poor creature here."

As Tiger headed for the earphones, Dal and Jack went to work once again, checking the blood and other body fluids from the stricken Bruckian. But now, incredibly, the results of their tests were quite different from those they had obtained before. The blood sugar and protein determinations fell into the pattern they had originally expected for a creature of this type. Even more surprising, the level of the antibody against the plague virus was high--far higher than it could have been from the tiny amount that was injected into the creature.

"They must have been making it themselves," Dal said, "and our inoculation was just the straw that broke the camel's back. All of those people must have been on the brink of symptoms of the infection, and all we did was add to the natural defenses they were already making."

"Then why did the symptoms appear?" Jack said. "If that's true, we should have been _helping_ them, and look at them now!"

Tiger appeared at the door, scowling. "We've got real trouble, now," he said. "I can't get through to a hospital ship. In fact, I can't get a message out at all. These people are jamming our radios."

"But why?" Dal said.

"I don't know, but take a look outside there."

Through the viewscreen it seemed as though the whole field around the ship had filled up with the crowd. The first reaction of terror now seemed to have given way to blind fury; the people were shouting angrily, waving their clenched fists at the ship as the spokesman tried to hold them back.

Then there was a resounding crash from somewhere below, and the ship lurched, throwing the doctors to the floor. They staggered to their feet as another blow jolted the ship, and another.

"Let's get a screen up," Tiger shouted. "Jack, get the engines going.

They're trying to board us, and I don't think it'll be much fun if they ever break in."

In the control room they threw the switches that activated a powerful protective energy screen around the ship. It was a device that was carried by all GPP Ships as a means of protection against physical attack. When activated, an energy screen was virtually impregnable, but it could only be used briefly; the power it required placed an enormous drain on a ship's energy resources, and a year's nuclear fuel could be consumed in a few hours.

Now the screen served its purpose. The ship steadied, still vibrating from the last a.s.sault, and the noise from below ceased abruptly. But when Jack threw the switches to start the engines, nothing happened at all.

"Look at that!" he cried, staring at the motionless dials. "They're jamming our electrical system somehow. I can't get any turn-over."

"Try it again," Tiger said. "We've got to get out of here. If they break in, we're done for."

"They can't break through the screen," Dal said.

"Not as long as it lasts. But we can't keep it up indefinitely."

Once again they tried the radio equipment. There was no response but the harsh static of the jamming signal from the ground below. "It's no good," Tiger said finally. "We're stuck here, and we can't even call for help. You'd think if they were so scared of us they'd be glad to see us go."

"I think there's more to it than that," Dal said thoughtfully. "This whole business has been crazy from the start. This just fits in with all the rest." He picked Fuzzy off his perch and set him on his shoulder as if to protect him from some unsuspected threat. "Maybe they're afraid of us, I don't know. But I think they're afraid of something else a whole lot worse."