"You're sure?" Domgraf-Schwach asked. "You really know which is the negative control sample?"

"I know." Fisher noted his findings on the punch sheet and moved away.

"I'm next," Tate said, impatiently pushing up. "Let's get this over with."

One by one, the men examined the two samples, recorded their findings, and then moved off to stand waiting uneasily.

"All right," Portbane said finally. "I'm the last one." He peered down briefly, scribbled his results, then pushed the equipment away. "Give me the readings," he told the workmen by the scanner.

A moment later, the findings were flashed up for everyone to see.

Fisher A

Tate A

O'Keefe B

Horstokowski B

Silberman B

Daniels B

Portbane A

Domgraf-Schwach B

Lanoir A

"I'll be damned," Silberman said softly. "As simple as that. We're paranoids."

"You cluck!" Tate shouted at Horstokowski. "It was A, not B! How the hell could you get it wrong?"

"B was as bright as a searchlight!" Domgraf-Schwach answered furiously. "A was completely colorless!"

O'Keefe pushed forward. "Which was it, Portbane? Which was the positive sample?"

"I don't know," Portbane confessed. "How could any of us be sure?"

The buzzer on Domgraf-Schwach's desk clicked and he snapped on the vidscreen.

The face of a soldier-operator appeared. "The attack's over, sir. We drove them away."

Domgraf-Schwach smiled ironically. "Catch any of them?"

"No, sir. They slipped back into the bog. I think we hit a couple, though. We'll go out tomorrow and try to find the corpses."

"You think you'll find them?"

"Well, the bog usually swallows them up. But maybe this time—"

"All right," Domgraf-Schwach interrupted. "If this turns out to be an exception, let me know." He broke the circuit.

"Now what?" Daniels inquired icily.

"There's no point in continuing work on the ship," O'Keefe said. "Why waste our time bombing empty bogs?"

"I suggest we keep working on the ship," Tate contradicted.

"Why?" O'Keefe asked.

"So we can head for Fomalhaut and give ourselves up to the hospital station."

Silberman stared at him incredulously. "Turn ourselves in? Why not stay here? We're not harming anybody."

"No, not yet. It's the future I'm thinking of, centuries from now."

"We'll be dead."

"Those of us in this room, sure, but what about our descendants?"

"He's right," Lanoir conceded. "Eventually our descendants will fill this whole solar system. Sooner or later, our ships might spread over the Galaxy." He tried to smile,

but his muscles would not respond. "The tapes point out how tenacious paranoids are. They cling fanatically to their fixed beliefs. If our descendants expand into Terran regions, there'll be a fight and we might win because we're more one-track. We would never deviate."

"Fanatics," Daniels whispered.

"We'll have to keep this information from the rest of the camp," O'Keefe said.

"Absolutely," Fisher agreed. "We'll have to keep them thinking the ship is for H-bomb attacks. Otherwise, we'll have one hell of a situation on our hands."

They began moving numbly toward the sealed door.

"Wait a minute," Domgraf-Schwach said urgently. "The two workmen." He started back, while some of them went out into the corridor, the rest back toward their seats.

And then it happened.

Silberman fired first. Fisher screamed as half of him vanished in swirling particles of radioactive ash. Silberman dropped to one knee and fired up at Tate. Tate leaned back and brought out his own B-pistol. Daniels stepped from the path of Lanoir's beam. It missed him and struck the first row of seats.

Lanoir calmly crept along the wall through the billowing clouds of smoke. A figure loomed ahead; he raised his gun and fired. The figure fell to one side and fired back. Lanoir staggered and collapsed like a deflated balloon and Silberman hurried on.

At his desk, Domgraf-Schwach was groping wildly for his escape button. His fingers touched it, but as he depressed the stud, a blast from Portbane's pistol removed the top of his head. The lifeless corpse stood momentarily, then was whisked to "safety" by the intricate apparatus beneath the desk.

"This way!" Portbane shouted, above the sizzle of the B-blasts. "Come on, Tate!"

Various beams were turned in his direction. Half the chamber burst apart and thundered down, disintegrating into rubble and flaming debris. He and Tate scrambled for one of the emergency exits. Behind them, the others hurried, firing savagely.

Horstokowski found the exit and slid past the jammed lock. He fired as the two figures raced up the passage ahead of him. One of them stumbled, but the other grabbed at him and they hobbled off together. Daniels was a better shot. As Tate and Portbane emerged on the surface, one of Daniels' blasts undercut the taller of the two.

Portbane continued running a little way, and then silently pitched face-forward against the side of a plastic house, a gloomy square of opaque blackness against the night sky.

"Where'd they go?" Silberman demanded hoarsely, as he appeared at the mouth of the passage. His right arm had been torn away by Lanoir's blast. The stump was seared hard.

"I got one of them." Daniels and O'Keefe approached the inert figure warily. "It's Portbane. That leaves Tate. We got three of the four. Not bad, on such short notice."

"Tate's damn smart," Silberman panted. "I think he suspected."

He scanned the darkness around them. Soldiers, returning from the gas attack, came hurrying up. Searchlights rumbled toward the scene of the shooting. Off in the distance, sirens wailed.

"Which way did he go?" Daniels asked.

"Over toward the bog."

O'Keefe moved cautiously along the narrow street. The others came slowly behind.

"You were the first to realize," Horstokowski said to Silberman. "For a while, I believed the test. Then I realized we were being tricked—the four of them were plotting in unison."

"I didn't expect four of them," Silberman admitted. "I knew there was at least one Terran spy among us. But Lanoir ..."

"I always knew Lanoir was a Terran agent," O'Keefe declared flatly. "I wasn't surprised at the test results. They gave themselves away by faking their findings."

Silberman waved over a group of soldiers. "Have Tate picked up and brought here. He's somewhere at the periphery of the camp."

The soldiers hurried away, dazed and muttering. Alarm bells dinned shrilly on all sides. Figures scampered back and forth. Like a disturbed ant colony, the whole camp was alive with excitement.

"In other words," Daniels said, "the four of them really saw the same as we. They saw B as the positive sample, but they put down A instead."

"They knew we'd put down B," O'Keefe said, "since B was the positive sample taken from the attack site. All they had to do was record the opposite. The results seemed to substantiate Lanoir's paranoid theory, which was why Portbane set up the test in the first place. It was planned a long time ago—part of their overall job."

"Lanoir dug up the tapes in the first place!" Daniels exclaimed. "Fisher and he planted them down in the ruins of the ship. Portbane got us to accept his testing device."

"What were they trying to do?" Silberman asked suddenly. "Why were they trying to convince us we're paranoids?"

"Isn't it obvious?" O'Keefe replied. "They wanted us to turn ourselves in. The Terran monkey men naturally are trying to choke off the race that's going to supplant them. We won't surrender, of course. The four of them were clever—they almost had me convinced. When the results flashed up five to four, I had a momentary doubt. But then I realized what an intricate strategy they had worked out."