Philip stared at her, scared to death. His wife had lost her mind.

"Now, now, sweetheart," he said soothingly, "let's get this straight. They fired a lab boy today. They found four of our rats in his home. He told some idiotic story of having 'found' them, with the others missing, running loose on the street that night, but of course he stole them. He must have sold the rest of them to other kids; they're working on that now."

Norah blew her nose and wiped her eyes. She had regained her usual calm.

"Philip Vinson," she said coldly, "are you accusing me of lying, or just of being crazy? I'm neither. I saw and heard those rats. They're here now. What's more, I guess I know where that oatmeal went, and the eggs and bacon too, and the cheese. I'm—I'm a hostage!

"I don't suppose," she added sarcastically, "that your SK540 was one of the ones they found in the boy's home?"

"No, it wasn't," he acknowledged uneasily. A nasty little icy trickle stole down his spine. "All right, Norah, I give in. You take the poker and I'll take the hammer, and we'll search this house from cellar to attic."

"You won't find them," said Norah bitterly. "SK540's too smart. They'll stay inside the walls and keep quiet."

"Then we'll find the holes they went through and rout them out."

They didn't, of course. There wasn't a sign of a rathole, or of a rat.

They got through dinner and the evening somehow. Norah put all the food not in cans inside the old-fashioned icebox which took the place of a refrigerator. Philip thought he was too disturbed to be able to sleep, but he did, and Norah, exhausted, was asleep as soon as her head touched the pillow.

His last doubt of his wife's sanity vanished when, the next morning, they found the icebox door open and half the food gone.

"That settles it!" Philip announced. "Come on, Norah, put your coat on. You're coming with me to the lab and we'll report what's happened. They'll find those creatures if they have to tear the house apart to do it. That boy must have been telling the truth."

"You couldn't keep me away," Norah responded. "I'll never spend another minute alone in this house while those dreadful things are in it."

But of course when they got to the front door, there they were, circling them, their teeth bared. The same with the back door and all the first floor windows.

"That's SK540 all right, leading them," Philip whispered through clenched jaws. He could smash them all, he supposed, in time, with what weapons he had. But he worked in the laboratory. He knew their value to science, especially SK540's.

Rats couldn't talk, he knew, and they couldn't understand human speech. Nevertheless, some kind of communication might establish itself. SK540's eyes were too intelligent not to believe that he was getting the gist of talk directed to him.

"This is utterly ridiculous," Philip grated. "If you won't let us out, how can we keep bringing food into the house for you? We'll all starve, you and we together."

He could have sworn SK540 was considering. But he guessed the implicit answer. Let either one of them out, now they knew the rats were there, and men from the laboratory would come quickly and overwhelm and carry off the besiegers. It was a true impasse.

"Philip," Norah reminded him, "if you don't go to work, they know we haven't a phone, and somebody will be here pretty soon to find out if anything's wrong."

But that wouldn't help, Philip reflected gloomily; they'd let anyone in, and keep him there.

And he thought to himself, and was careful not to say it aloud: rats are rats. Even if they are 25th generation laboratory-born. When the other food was gone there would be human meat.

He did not want to look at them any more. He took Norah's arm and turned away into their bedroom.

They stayed there all day, too upset to think of eating, talking and talking to no conclusion. As dusk came on they did not light the gas. Exhausted, they lay down on the bed without undressing.

After a while there was a quiet scratching at the door.

"Don't let them in!" Norah whispered. Her teeth were chattering.

"I must, dear," he whispered back. "It isn't 'them,' I'm sure of it—it's just SK540 himself. I've been expecting him. We've got to reach some kind of understanding."

"With a rat?"

"With a super-rat. We have no choice."

Philip was right. SK540 alone stood there and sidled in as the door closed solidly again behind him.

How could one communicate with a rat? Philip could think of no way except to pick him up, place him where they were face to face, and talk.

"Are your—followers outside?" he asked.

A rodent's face can have no expression, but Philip caught a glance of contempt in the beady eyes. The slaves were doubtless bedded down in their hideaway, with strict orders to stay there and keep quiet.

"You know," Philip Vinson went on, "I could kill you, very easily." The words would mean nothing to SK540; the tone might. He watched the beady eyes; there was nothing in them but intelligent attention, no flicker of fear.

"Or I could tie you up and take you to the laboratory and let them decide whether to keep you or kill you. We are all much bigger and stronger than you. Without your army you can't intimidate us."

There was, of course, no answer. But SK540 did a startling and touching thing. He reached out one front paw, as if in appeal.

Norah caught her breath in astonishment.

"He—he just wants to be free," she said in a choked whisper.

"You mean you're not afraid of him any more?"

"You said yourself he couldn't intimidate us without his army."

Philip thought a minute. Then he said slowly:

"I wonder if we had the right to do this to him in the first place. He would have been an ordinary laboratory rat, mindless and contented; we've made him into a neurotic alien in his world."

"You're not responsible, darling; you're a technician, not a biochemist."

"I share the responsibility. We all do."

"So what? The fact remains that it was done, and here he is—and here we are."

The doorbell rang.

Philip and Norah exchanged glances. SK540 watched them.

"It's probably Kelly, from the lab," Philip said, "trying to find out why I wasn't there today. It's just about quitting time, and he lives nearest us."

Norah astonished him. She picked up SK540 from the bed-side table where Philip had placed him, and hid him under her pillow.

"Get rid of whoever it is," she said defensively. Philip stared for an instant, then walked briskly downstairs. He was back in a few minutes.

"It was Kelly, all right," he told her. "I said you were sick and I couldn't leave you to phone. I said I'd be there tomorrow. Now what?"

SK540's white whiskers emerged from under the pillow, and he jumped over to the table again. Norah's cheeks were pink.

"When it came to the point, I just couldn't," she explained shamefacedly. "I suddenly realized that he's a person. I couldn't let him be taken back to prison."

"Aren't you frightened any more?"

"Not of him." She faced the super-rat squarely. "Look," she said, "if we take care of you, will you get rid of that gang of yours, so we can be free too?"

"That's nonsense, Norah," Philip objected. "He can't possibly understand you."

"Dogs and cats learn to understand enough, and he's smarter than any dog or cat that ever lived."

"But—"

The words froze on his lips. SK540 had jumped to the floor and run to the door. There he stood and looked back at them, his tail twitching.

"He wants us to follow him," Norah murmured.

There was no sign of a hole in the back wall of the disused pantry. But behind it they could hear squeaks and rustlings.

SK540 scratched delicately at almost invisible cracks. A section of the wall, two by four inches, fell out on the floor.

"So that's where some of the oatmeal went," Norah commented. "Made into paste."

"Sh!"

SK540 vanished through the hole. They waited, listening to incomprehensible sounds. Outside it had grown dark.

Then the leader emerged and stood to one side of the long line that pattered through the hole. The two humans stared, fascinated, as the line made straight for the back door and under it. SK540 stayed where he was.

"Will they go back to the lab?" Norah asked.

Philip shrugged.

"It doesn't matter. Some of them may ... I feel like a traitor."

"I don't. I feel like one of those people who hid escaped war prisoners in Europe."

When the rats were all gone, they turned to SK540. But without a glance at them he re-entered the hiding-place. In a minute he returned, herding two white rats before him. He stood still, obviously expectant.

Philip squatted on his heels. He picked up the two refugees and looked them over.

"Both females," he announced briefly. "And both pregnant."

"Is he the father?"

"Who else? He'd see to that."

"And will they inherit his—his—"

"His 'super-ratism'? That's the whole point. That's the object of the entire experiment. They were going to try it soon."

The three white rats had scarcely moved. The two mothers-to-be had apparently fallen asleep. Only SK540 stood quietly eying the humans. When they left him to find a place where they could talk in private he did not follow them.

"It comes down to this," Philip said at the end of half an hour's fruitless discussion. "We promised him, or as good as. He believed us and trusted us.

"But if we keep to our promise we're really traitors—to the human race."

"You mean, if the offspring should inherit his brain-power, they might overrun us all?"

"Not might. Would."

"So—"

"So it's an insoluble problem, on our terms. We have to think of this as a war, and of them as our enemies. What is our word of honor to a rat?"

"But to a super-rat—to SK540—"

As if called, SK540 appeared.

Had he been listening? Had he understood? Neither of them dared to voice the question aloud in his presence.

"Later," Philip murmured.

"We must eat," said Norah. "Let's see what's left in the way of food."

Everything tasted flat; they weren't very hungry after all. There was enough left over to feed the three rats. But they had evidently helped themselves earlier; they left the scraps untasted.

Neither of the humans guessed what else had vanished from the pantry shelves—what, when he had heard enough, SK540 had slipped away and sprinkled on the remaining contents of the icebox, wherever the white powder would not show.

They did not know until it was too late—until both of them lay writhing in their last spasms on their bedroom floor.

By the time the house was broken into and their bodies found, SK540 and his two wives were far away, and safe....

And this, children, is the true account, handed down by tradition from the days of our great Founder, of how the human race ceased to exist and we took over the world.