"Do you?"

Again, Garwood's reflex was to lie. "I think so," he admitted instead. "I'm pretty close, anyway."

They walked on in silence for a few more paces. "I'm sure you realize," Davidson said at last, "the implications of what you're saying."

Garwood sighed. "Do try to remember, Major, that I was worrying about all this long before you were even on the scene."

"Perhaps. But my experience with scientists has been that you often have a tendency toward tunnel vision, so it never hurts to check. Have you told anyone yet? Or left any hard copies of the technique?"

"No, to both."

"Well, that's a start." Davidson threw him a sideways look. "Unfortunately, it won't hold anyone for long.

If I'm smart enough to figure out what the increase in the Garwood Effect implies, Saunders is certainly smart enough to do the same."

Garwood looked over at Davidson's face, and the knot in his stomach tightened further as he remembered what the other had once said about Saunders using hypnosis against him. "Then I have to get away again before that happens," he said in a quiet voice.

Davidson shook his head. "That won't be easy to do a second time."

"Then I'll need help, won't I?"

Davidson didn't reply for several seconds. "Perhaps," he said at last. "But bear in mind that above everything else I have my duty to consider."

"I understand," Garwood nodded.

Davidson eyed him. "Do you, Doctor? Do you really?"

Garwood met his eyes... and at long last, he really did understand.

Davidson wasn't offering him safe pa.s.sage to that mythical wilderness Garwood had so often longed for.

He was offering only to help Garwood keep the secret of time travel out of Saunders's grasp. To keep it away from a world that such a secret would surely destroy.

Offering the only way out that was guaranteed to be permanent.

Garwood's heart was thudding in his ears, and he could feel sweat gathering on his upper lip. "And when," he heard himself say, "would your duty require you to take that action?"

"When it was clear there was no longer any choice," Davidson said evenly. "When you finally proved safe time travel was impossible, for instance. Or perhaps when you showed a working time machine could be built."

They'd reached the door to Garwood's office now. "But if I instead proved that the probability-shift effect would in fact keep a working time machine from actually being built?" Garwood asked, turning toface the other. "What then?"

"Then it's not a working time machine, is it?" Davidson countered.

Garwood took a deep breath. "Major... I want a working time machine built even less than you do.

Believe me."

"I hope so," Davidson nodded, his eyes steady on Garwood's. "Because you and I may be the only ones here who feel that way... and speaking for myself, I know only one way to keep your equations from bringing chaos onto the world. I hope I don't have to use it."

A violent shiver ran up Garwood's back. "I do, too," he managed. Turning the doork.n.o.b with a shaking hand, he fled from Davidson's eyes to the safety of his office.

To the relative safety, anyway, of his office.

For several minutes he paced the room, his pounding heart only gradually calming down. A long time ago, before his break from Backdrop, he'd contemplated suicide as the only sure way to escape the cloud of destruction around him. But it had never been a serious consideration, and he'd turned instead to his escape-and-research plan.

A plan which had eventually ended in failure. And now, with the stakes even higher than they'd been back then, death was once again being presented to him as the only sure way to keep the genie in the bottle.

Only this time the decision wasn't necessarily going to be his. And to add irony to the whole thing, Davidson's presence here was ultimately his own fault. If he hadn't skipped out of Backdrop six months ago, the major would never even have come onto the scene.

Or maybe he would have. With the contorted circular logic that seemed to drive the probability-shift effect nothing could be taken for granted. Besides, if Davidson hadn't caught him, perhaps someone less intelligent would have. Someone who might have brushed aside his fears and forced him onto that airplane at Chanute AFB. If that had happened*if the effect had then precipitated a crashHe shook his head to clear it. It was, he thought bitterly, like the old college bull sessions about free will versus predestination. There were no answers, ever; and you could go around in circles all night chasing after them. On one hand, the probability-shift effect could destroy engines; on the other, as Davidson himself had pointed out, it logically shouldn't be able to crash a plane that Garwood himself was on...

Garwood frowned, train of thought breaking as a wisp of something brushed past his mind. Davidson...

airplane...?

And with a sudden flood of adrenaline, the answer came to him.

Maybe.

Deep in thought, he barely noticed the knock at the door. "Who is it?" he called mechanically.

"Saunders," the other's familiar voice came through the panel.

Garwood licked his lips, shifting his mind as best he could back to the real world. The next few minutes could be crucial ones indeed.... "Come in," he called."I got a message that you wanted to see me," Saunders said, glancing toward the terminal as he came into the room. "More equipment trouble?"

"Always," Garwood nodded, waving him to a chair. "But that's not why I called you here. I think I may have some good news."

Saunders's eyes probed Garwood's face as he sank into the proffered seat. "Oh? What kind?"

Garwood hesitated. "It'll depend, of course, on just what kind of lat.i.tude you're willing to allow me*how much control I'll have on this*and I'll tell you up front that if you buck me you'll wind up with nothing. Understand?"

"It would be hard not to," Saunders said dryly, "considering that you've been making these same demands since you got here. What am I promising not to interfere with this time?"

Garwood took a deep breath. "I'm ready," he said, "to build you a time machine."

VI.

Within a few days the Garwood Effect damage that had been occurring sporadically throughout Backdrop's several fabrication areas jumped nearly eight hundred percent. A few days after that, repair and replacement equipment began to be shipped into the complex at a correspondingly increased rate, almost*but not quite*masking the even more dramatic flood of non-damage-control shipping also entering Backdrop. The invoice lists for the latter made for interesting reading: esoteric electronic and mechanical equipment, exotic metals, specialized machine tools for both macro and micro work, odd power supplies*it ran the entire gamut.

And for Davidson, the invoices combined with the damage reports were all the proof he needed.

Garwood had figured out how to build his time machine. And was building it.

d.a.m.n him. Hissing between his teeth, Davidson leaned wearily back into his chair and blanked the last of the invoices from his terminal screen. So Garwood had been lying through his teeth all along. Lying about his fears concerning time travel; lying about his disagreements with Dr. Saunders; lying about how n.o.ble and self-sacrificing he was willing to be to keep the world safe from the wildfire Garwood Effect a time machine would create.

And Davidson, that supposedly expert reader of people, had fallen for the whole act like a novice investigator.

Firmly, he shook the thought away. Bruised pride was far and away the least of his considerations at the moment. If Garwood was building a time machine...

But could he in fact build it?

Davidson gnawed at the inside of his cheek, listening to the logic spin in circles in his head. Garwood had suggested more than once that the Garwood Effect would destroy a time machine piecemeal before it could even be a.s.sembled. Had he been lying about that, too? It had seemed reasonable enough at the time... but then why would he and Saunders even bother trying? No, there had to be something else happening, something Garwood had managed to leave out of his argument and which Davidson hadn't caught on his own.But whatever it was he'd missed, circ.u.mstances still left him no choice. Garwood had to be stopped.

Taking a deep breath, Davidson leaned forward to the terminal again and called up Backdrop's cafeteria records. If Garwood was working around the clock, as Davidson certainly would be doing in his place...

and after a few tries he found what he was looking for: the records of the meals delivered to the main a.s.sembly area at the end of Backdrop's security tunnel. Scanning them, he found there had been between three and twelve meals going into the tunnel each mealtime since two days before the dramatic upsurge in Garwood Effect damage.

And Garwood's ordering number was on each one of the order lists.

Davidson swore again, under his breath. Of course Garwood would be spending all his time down the tunnel*after their last conversation a couple of weeks ago the man would be crazy to stay anywhere that Davidson's security clearance would let him get to. And he'd chosen his sanctuary well.

Down the security tunnel, buried beneath the a.s.sembly area's artificial hill, it would take either a company of Marines or a medium-sized tactical nuke to get to him now.

Or maybe*just maybe*all it would take would be a single man with a computer terminal.

A man with some knowledge of security systems, some patience, and some time.

Davidson gritted his teeth. The terminal he had; and the knowledge, and the patience. But as for the time... he would know in a few days.

If the world still existed by then.

VII.

The five techs were still going strong as the clocks reached midnight, but Garwood called a halt anyway.

"We'll be doing the final wiring a.s.sembly and checkout tomorrow," he reminded them. "I don't want people felling asleep over their voltmeters while they're doing that."

"You really expect any of us to sleep?" one of the techs grumbled half-seriously.

"Well, I sure will," Garwood told him lightly, hooking a thumb toward the door. "Come on, everybody out. See you at eight tomorrow morning. Pleasant dreams."

The tech had been right, Garwood realized as he watched them empty their tool pouches onto an already cluttered work table: with the project so close to completion they were going to be too wired up for easy sleep. But fortunately they were as obedient as they were competent, and they filed out without any real protest.

And Garwood was alone.

Exhaling tiredly, he locked the double doors and made his way back to the center of the huge sh.o.r.ed-up fabrication dome and the lopsided monstrosity looming there. Beyond it across the dome was his cot, beckoning him temptingly... Stepping instead to the cluttered work table, he picked up a screwdriver set and climbed up through the tangle of equipment into the seat at its center. Fifteen minutes later, the final connections were complete.

It was finished.

For a long minute he just sat there, eyes gazing unseeingly at the simple control/indicator panel beforehim. It was finished. After all the blood, sweat, and tears*after all the arguments with Saunders*after the total disruption of his life... it was done.

He had created a time machine.

Sighing, he climbed stiffly down from the seat and returned the screwdrivers to their place on the work table. The next table over was covered with various papers; snaring a wastebasket, he began pushing the papers into it, tamping them down as necessary until the table was clear. A length of electrical cable secured the wastebasket to a protruding metal plate at the back of the time machine's seat, leaving enough room for the suitcase and survival pack he retrieved from beneath his cot. Two more lengths of cable to secure them... and there was just one more ch.o.r.e to do. A set of three video cameras stood s.p.a.ced around the room, silent on their tripods; stepping to each in turn, he turned all of them on.

He was just starting back to the time machine when there was a faint sound from the double doors.

He turned, stomach tightening into a knot. It could only be Saunders, here for a late-night briefing on the day's progress. If he noticed that the cameras were running*realized what that meantThe doors swung open, and Major Davidson stepped in.

Garwood felt an instantaneous burst of relief... followed by an equally instantaneous burst of fear. He'd specifically requested that Davidson not be cleared for this part of Backdrop... "Major," he managed to say between suddenly dry lips. "Up*ah, rather late, aren't you?"

Davidson closed the doors, his eyes never leaving Garwood's face. "I only hope I'm not here too late,"

he said in a quiet voice. "You've done it, haven't you?"

Garwood licked his lips, nodding his head fractionally toward the machine beside him. "Here it is."

For a long moment neither man spoke. "I misjudged you," Davidson said at last, and to Garwood's ears there was more sorrow than anger in the words. "You talked a lot about responsibility to the world; but in the end you backed down and did what they told you to do."

"And you?" Garwood asked softly, the tightness in his stomach beginning to unknot. If Davidson was willing to talk first... to talk, and to listen... "Have you thought through the consequences of your actions?

You went to a lot of illegal trouble to get in here. If you kill me on top of that, your own life's effectively over."

A muscle in Davidson's cheek twitched. "Unlike you, Doctor, I don't just talk about responsibility. And there are things worth dying for."

Unbidden, a smile twitched at Garwood's lips. "You know, Major, I'm glad you came. It gives me a certain measure of hope to know that even in the midst of the 'not-me' generation there are still people willing to look beyond their own selfish interests."

Davidson snorted. "Doctor, I'll remind you that I've seen this n.o.bility act of yours before. I'm not buying it this time."

"Good. Then just listen."

Davidson frowned. "To what?"

"To the silence.""The*?" Davidson stopped abruptly; and all at once he seemed to get it. "It's quiet," he almost whispered, eyes darting around the room, coming to rest eventually on the machine beside Garwood.

"But*the Garwood Effect*you've found a way to stop it?"

Garwood shook his head. "No, not really. Though I think I may understand it a bit better now." He waved a hand around the room. "In a sense, the trouble is merely that I was born at the wrong time. If I'd lived a hundred years earlier the culture wouldn't have had the technological base to do anything with my equations; if I'd been born a hundred years later, perhaps I'd have had the time and necessary mathematics to work out a safe method of time travel, leaving my current equations as nothing more than useless curiosities to be forgotten."

"I'd hardly call them useless," Davidson interjected.

"Oh, but they are. Or didn't you notice how much trouble the various fabrication shops had in constructing the modules for this machine?"

"Of course I did," Davidson nodded, a frown still hovering across his eyes. "But if the modules themselves were falling apart...?"

"How was I able to a.s.semble a working machine?" Garwood reached up to touch one of the machine's supports. "To be blunt, I cheated. And as it happens, you were the one who showed me how to do it."

Davidson's eyes locked with him. "Me?"

"You," Garwood nodded. "With a simple, rather sarcastic remark you made to me back in my Champaign apartment. Tell me, what's the underlying force that drives the Garwood Effect?"

Davidson hesitated, as if looking for a verbal trap. "You told me it was the possibility that someone would use time travel to change the past*" He broke off, head jerking with sudden insight. "Are you saying...?"

"Exactly," Garwood nodded. "There's no possibility of changing the past if my machine can only take me into the future."