The old man’s whisper was hoarse and breathless. His hands quivered on the knobs, and the fourth pip outward from the disk crept to the center of the field. It grew, and the others spread away. It began to tremble like Sledge’s hands.

“Sit very still,” came his rasping whisper. “Hold your breath. Nothing must disturb the needle.” He reached cautiously for another knob, and his first touch set the greenish image to dancing violently. He drew his hand back to knead and flex it with the other.

“Watch!” His whisper was hushed and strained. He nodded at the window. “Tell me when they stop.”

Reluctantly, Underhill dragged his eyes from that intense gaunt figure and that harmless-seeming toy. He looked out again, at two or three little black mechanicals busy about the shining roofs across the alley.

He waited for them to stop.

He didn’t dare to breathe. He felt the loud, hurried hammer of his heart and the nervous quiver of his muscles. Trying to steady himself, he tried not to think of the world about to be exploded, so far away that the flash would not reach this planet for another century and longer. The loud hoarse voice startled him:

“Have they stopped?”

He shook his head, and breathed again. Carrying their unfamiliar tools and strange materials, the small black machines were still busy across the alley, building an elaborate cupola above that glowing crimson dome.

“They haven’t stopped,” he said.

“Then we’ve failed.” The old man’s voice was thin and ill. “I don’t know why.”

The door rattled, then. They had locked it, but the flimsy bolt was intended only to stop men. Metal snapped. The door swung open. A black mechanical came in, on soundless graceful feet. Its silvery voice purred softly:

“At your service, Mr. Sledge.”

The old man stared at it with glazing, stricken eyes.

“Get out of here! ” he rasped bitterly. “I forbid you—”

Ignoring him, it darted to the kitchen table. With a flashing certainty of action, it turned two knobs on the director. The oscilliscope went dark. The palladium needle started spinning aimlessly. Deftly it snapped a soldered connection next to the thick lead ball, and then its blind steel eyes turned to Sledge.

“You were attempting to break the Prime Directive.” Its brightly gentle voice held no accusation, no malice or anger. “The injunction to respect your freedom is subordinate to the Prime Directive, as you know. It is therefore imperative for us to interfere.”

The old man turned ghastly. His head was shrunken and cadaverous and blue, as if all the juice of life had been drained away, and his eyes in their pit-like sockets had a wild, glazed stare. His breath became a ragged, laborious gasping.

“How—?” His voice was a feeble mumbling. “How did—?”

The little machine, standing black and bland and utterly unmoving, told him cheerfully:

“We learned about rhodomagnetic screens from that man who came to kill you, back on Wing IV. The Central is shielded, now, against your catalytic beam.”

With lean muscles jerking convulsively on his gaunt frame, old Sledge had come to his feet from the high stool. He stood hunched and swaying, no more than a shrunken human husk, gasping painfully for life, staring wildly into the blind steel eyes of the humanoid. He gulped. His lax blue mouth opened and closed, but no voice came.

“We have always been aware of your dangerous project,” the silvery tones dripped softly, “because now our senses are keener than you made them. We allowed you to complete it, because the integration process will ultimately become necessary for our full discharge of the Prime Directive. The supply of heavy metals for our fission plants is limited, but now we shall be able to draw unlimited power from catalytic fission.”

The old man crumpled, as if from an unendurable blow.

“Huh?” Sledge shook himself, groggily. “What’s that?”

“Now we can serve men forever,” the black thing cooed serenely, “on every world of every star.”

He fell. The slim, blind mechanical stood motionless, making no effort to help him. Underhill was farther away, but he ran up in time to catch the stricken man before his head struck the floor.

“Get moving!” His shaken voice came strangely calm. “Get Dr. Winters.”

The humanoid didn’t move.

“The danger to the Prime Directive is ended, now,” it purred. “Therefore it is impossible for us to aid or to hinder Mr. Sledge, in any way whatever.”

“Then call Dr. Winters for me,” rapped Underhill.

“At your service,” it agreed.

But the old man, laboring for breath on the floor, whispered faintly:

“No time—no use! I’m beaten—done—a fool. Blind as a humanoid. Tell them—to help me. Giving up—my immunity. No use—anyhow. All—humanity—finished!”

Underhill gestured, and the sleek black thing darted in solicitous obedience to kneel by the man on the floor.

“You wish to surrender your special privileges?” it murmured brightly. “You wish to accept our total service for yourself, Mr. Sledge, under the Prime Directive?”

Laboriously, Sledge nodded, laboriously whispered, “I do.”

Black mechanicals, at that, came swarming into the shabby little rooms. One of them tore off Sledge’s sleeve to swab his arm. Another brought a tiny hypodermic to give an injection. Then they picked him up gently and carried him away.

Several humanoids remained in the little apartment, now a sanctuary no longer. Most of them had gathered about the useless integrator. Carefully, as if their special senses were studying every detail, they began taking it apart.

One little mechanical, however, came over to Underhill. It stood motionless in front of him, staring through him with sightless metal eyes. His legs began to tremble. He swallowed uneasily.

“Mr. Underhill,” it cooed benevolently, “why did you help with this?”

He gulped and answered bitterly:

“Because I don’t like you, or your damned Prime Directive. Because you’re choking the life out of all mankind. I—I wanted to stop it.”

“Others have protested,” it purred softly. “But only at first. In our efficient discharge of the Prime Directive, we have learned how to make all men happy.”

Underhill stiffened defiantly.

“Not all!” he muttered. “Not quite!”

The dark graceful oval of its face was fixed in a look of alert benevolence and perpetual mild amazement. Its silvery voice was warm and kind.

“Like other human beings, Mr. Underhill, you lack discrimination of good and evil. You have proved that by your effort to break the Prime Directive. Now it will be necessary for you to accept our total service, without further delay.”

“All right,” he yielded—but he muttered a bitter reservation: “Smothering men with too much care won’t make them happy.”

Its soft voice challenged him brightly:

“Just wait and see, Mr. Underhill.”