you like the devil."

Arna's smile faded. She slipped out of his embrace. "Sy! Do you mean to say you risked exposure of the only Sur-Malic-type telepath that young Tel can receive, when you didn't need help?"

Sy evaded the question. "Tomorrow we can shoot over to Haldane," he suggested. "There's an old Earth clergyman there who got stranded when the Alliance broke off chummy relations with Leaguers."

Arna eyed him icily. "And why should we visit this clergyman?"

"Well," said Sy innocently, "the old guy's almost two hundred now, which is crowding the limit for his generation. And you know the Sur-Malic don't have any marriage cere—"

"Oh, you knobhead! Here you have the most critical job of anyone in the League, and—and—who said I was going to marry you, anyway?"

"I did," returned Sy promptly. "Remember? I've been telling you that since we were kids—and you never once denied it."

Arna made a sound that was partly a sob and partly a laugh. She shook her head unbelievingly. "With the fate of a galaxy depending on your abilities and judgment, you drag me across a thousand million miles of space to prate about marriage."

"Yes," admitted Sy, "but think of how far it might have been. If spatial distances were actually as great as the old astronomers used to think, before they learned that light slows down after it travels—"

There was no slightest chance that Arna's small hand would actually strike Sy. She knew the attempt was futile, but she tried her best—and uttered a rueful sound when the blow seemed to pass right through his cheek, while he apparently stood still, grinning. "Some day," she promised, "I'm going to shoot you in the back—just to see what happens."

"That sounds more like my cheerful little calc-bird," he said. "But let's wait till after we're married, huh?" They continued along the unpaved road.

"I think," Arna said levelly, "there will be no marriage. There will certainly be none for me until the completion of the unimportant, completely insignificant Operation Catskin—or," she finished sweetly, "have you given that any thought lately?"

Sy frowned. A small stone in the road suddenly sped along the ground and cracked against another; the other snapped away, rolled, slowed, reversed, shot backward and hit the first one. He spoke thoughtfully. "Yes, I've given it a great deal of thought. And there's going to be—uh—a slight change of plan. That's really why I needed you here, Arna."

The girl stared. "Sy! Have you shorted a circuit? For heaven's sake, don't you realize this thing has been planned, and calculated, and re-arranged bit by bit for twenty years? That each of us is merely a small—no matter how important—cog in a far-reaching activity of infinite complexity? Don't you understand that everything is in a state of delicate, constantly shifting balance, with ambassadors, scientists and agents making each tiny move with precise timing and skill throughout a hundred worlds? And you want to change things!" Her voice softened, and she laid a hand on his arm. "Sy," she pleaded, "if you've run into some insurmountable obstacle, let's report it and try to ease out without upsetting everything. That's happened three times before, you know, and it's no disgrace if you can't—"

"Hell!" said Sy bitterly. "I can do it—I think. And if I can do it at all, I can go one step better. But I need help."

"But can't you see, Sy, that you can't change the plans now? Why, no one even knows what you have in mind—and I won't have anything to do with it!"

The hangars loomed not far ahead. Sy spoke patiently. "Look. As it stands, Operation Catskin now boils down to installing new engines in the Sur-Malic fleet, slipping gimmicks into the stabilizer works and controlling the gimmicks psychokinetically when the League and Alliance fleets meet for battle. If the Alliance ships operate erratically, they can't bring their guns to bear, and the League will mop up—even with our pint-sized fleet and inferior armament. Check?"

"Of course. That's what—"

"Okay. Now suppose we can rig a deal so it won't be necessary to shoot up the Alliance boats nor kill the poor deluded devils in them? The League wins the war, gets a brand-new, superior fleet, and hardly anyone gets smeared."

Arna sighed. "Let's be practical, Sy. All you know about engineering has been implanted hypnotically just for this job; all I can do is answer questions of pure math. I wouldn't know how to devise any gadgetry, and you're in no position to waste time trying—and in war some must be destroyed that others may survive."

"But suppose I've just about got the thing whipped already? I've learned enough, since I've been here, to rate Mech C even home."

"Sy, I just won't be a party to anything that might possibly upset League plans!"

Sy's chest heaved resignedly. "Will you help me with the computational math needed to finish Operation Catskin?"

"That's better!" Arna squeezed his arm happily. "Of course I will, you big, bony, restless idealist!"

He smiled fondly at her—at her answer, her young beauty and her nearness.

The weeks passed swiftly—weeks in which the swarming Sur-Malic workmen ripped from their foundations the massive, cumbersome atomic converters of the mighty space fleet and replaced them with light, radically designed engines which would feed eternally upon the all-pervading cosmic emanations that streaked the universe.

Sy and Arna had worked furiously. Surrounded by a corps of physicists, mathematicians, engineers, technicians and draftsmen, Arna had unerringly replied to endless queries as fast as she could speak. Sy had translated equations, converted values, integrated, correlated and directed. Subtly, he had inserted certain innocent equations of his own bit by bit, fed his results into the basic plans and disguised the all-important device with the cloak of dual function—one of which was vital to ship performance, the other of which was vulnerable to his psychokinetic ability to move objects of small mass by mental concentration alone.

But all things are subject to the vagaries of pure chance. Commandant Rilth, as chief of the project, continually prowled the immense planning rooms, workshops and assembly areas, giving of his not-inconsiderable technical knowledge where needed. And one day he came upon Sy delicately checking the tiny installation which would spell doom to Alliance schemes of conquest.

"You have found a flaw, perhaps?" demanded the Sur-Malic officer. He squatted and peered through the maze of ducts and cables at the shielded mechanism.

Sy crawled back out of the metallic web. "Not yet," he grunted. "I was just testing my brainstorm—works like a charm."

"To me," sneered Rilth, "it looks clumsy and inefficient. Could not your addled brain devise an electronic circuit, instead of a mechanical device subject to frictional wear?"

Sy wiped the perspiration from a dripping brow and spoke boldly. "This simplifies the master controls for your stupid crewmen. See those little plates on the shaft—like a butterfly's wings? When they fold up, the ship revolves; the closer together they get, the greater the artificial gravity. When they touch, you've got normal gravity in the ship. They function perfectly—and if you don't like them, rip them out of every boat and design your own G control!"

Rilth smiled coldly. "I suppose we must accept some of the more imbecilic aspects of your warped genius." He turned on his heel and left.

Sy whispered at his retreating back. "You'll never know how warped until that butterfly folds its wings down—and they kiss like little angels."

As the gigantic task of installation hummed and whined and boiled its way to completion, Sy and Arna found time to slip away into sprawling, dirty