"Nothing!" Paul snapped. "Stay away from him. He's a murderer and I don't want him anywhere near you."

Joanna did not reply, hut Paul saw what she was thinking. He's my son.

That's the long and the short of it, Paul told himself. I'm her Husband, the father of the child she's carrying. But Greg is her son and she'll try to protect him even if he tries to kill her.

I've got get back there, he realized. Quick as I can. Got to get there and protect her.

Joanna could see the determination in Paul's exhausted face. He wants to get back here so he can accuse Greg. Greg tried to murder him.

Without consciously thinking about it, she tapped the phone console on her desk and called out her son's name. In a few seconds Greg's darkly handsome face appeared on the display screen.

"Could you come over to my office, Greg?" Joanna asked.

"I'm in the middle of-"

"Right now," Joanna snapped. Then she added, "Please."

Annoyance flashed across his features, but he held it in check and answered, "Certainly."

He looked more apprehensive than annoyed when he stepped into Joanna's office. She had hardly changed anything in the big corner room since taking it over from Bradley Arnold. There had been no time; Joanna had been much too busy learning her new responsibilities to deal with interior decorators.

Warily, with the same expression he had worn as a little boy when he'd been caught doing something he shouldn't, Greg walked across the richly patterned Indian carpet and took the leather chair in front of Joanna's desk.

"What's happened?" he asked softly.

"I just got a call from Moonbase," said Joanna.

His brows rose. "Oh?"

"It was Paul. He's still alive, but the two men working with him were killed."

Greg let out a long sigh. "Too bad."

"The nanomachines killed them."

"Yes."

"You know all about it," don't you?"

"Nanotechnology is very new, Mom. Untried. Accidents will happen."

Joanna stared at her son. "Paul thinks you tried to murder him."

"That's just like him."

"Did you use nanomachines to kill Brad?" Joanna heart herself ask.

The hint of a smile ghosted across Greg's lips. "The pompous old fool."

"Did you?"

Greg shifted slightly in the chair. "When I was in San Jose a few months ago I saw a demonstration of what they cal gobblers-nanobugs that can take the platinum atoms out of an old-fashioned automobile's catalytic converter."

"What's that got to do with Brad's death?"

He shrugged carelessly. "I've heard that jet engines have a lot of blades that are coated with platinum and tungsten and other metals. To resist heat, I think. If those metals erode away the engine blades break up."

"And that's what happened to Brad's plane?"

"At supersonic speed a sudden loss of power can be very dangerous," Greg said. Then he added, "So I'm told."

"Paul isn't dead," Joanna said. "He's coming back here and he's going to accuse you of murder."

For the first time something like fear showed in Greg's face. "He's got no proof..."

Joanna said, "Don't you think he'll find proof? Don't you think he'll find someone in the San Jose division who gave you a sampling of nanomachines? What do you call them, gobblers?"

Irritated, Greg answered, "I suppose the corporation's CEO can find employees who'll tell him what he wants to hear."

"Greg, two men have died!"

"Three," he said smugly, "counting Brad. More, come to think of it: there's the crew of his plane, too, isn't there?"

She stared at her son. I did this to him, Joanna thought. It's my fault as much as his. More. I've allowed my happy little boy to turn into a sick, sick man.

"You need help, Greg," she said.

"Yes," he said. "I suppose I do. Are you going to help me, Mom?"

"All that I can."

He leaned forward in his chair. "Then get rid of that monster you're carrying in your belly and get a divorce. You and I can run this corporation. Just the two of us. We don't need him or his spawn."

Shocked by his sudden intensity, Joanna could say nothing except, "I can't do that."

"Then I'll have to kill him."

Joanna studied his face. "Will you kill me, too?" He seemed surprised at the thought. "I could never harm you, "Mom. I've always tried to protect you. Even against Dad."

"Against... your father?"

"He deserved to die. He even wanted to die. But he was too weak to do it himself." Greg smiled the way he had when he brought home good marks from school. "So I helped him."

Joanna sank back in her swivel chair. Bradley Arnold's chair. Her son continued to smile at her as charmingly as the little boy who used to offer her flowers he plucked from their garden.

MARE NUBIUM.

Paul was thinking how different everything looked from the driver's seat of the tractor. The barren landscape rolled by not without jounces and bumps, but it was sure easier than walking. The tractor was a small one, without an enclosec cab. He had to keep his suit buttoned up against the vacuum But it beat walking by about a thousand lightyears.

Up ahead he could see the tired old mountains of the Alphonsus ringwall rising to meet him. Too far away to make out the winding ruts that marked Wodjohowitcz Pass, but he'd be there soon enough. The thought of Wojo and Tink tore at his memory. He'll pay for what he did, Paul promised himself. He'll pay if I have to kill him myself. He could feel the muscles of his jaw and neck tense. Whose side is Joanna going to take? Paul knew the answer. She'll protect the kidl all she can.

Some kid. He's a homicidal maniac.

The sudden shrill alarm in his helmet earphones startled him. Looking down at his forearm display he saw a red light blinking. Oxygen supply critical.

How the hell can that be? I topped off the tank before I left Tempo 19.

More annoyed than afraid, Paul followed the standard practice and plugged his auxiliary oxygen line into the tractor's standby tank. The shrilling in his earphones stopped.

What the hell happened to my backpack tank? he wondered. Or is it just a sensor crapped out?

He kept his real fear buried deep in the back of his mind. He knew it was there, knew what it was, but he didn't want to face it, deal with it, admit that it even existed.

For nearly half an hour he continued riding along the bleak, pockmarked plain. The ringwall mountains were really looming before him now. He could see the notch where they had come across on their way out.

The tractor's oxygen supply was okay, he saw with a glance at the control panel. He reached around with one hand to check the hose, from his backpack tank. Maybe it came loose, all the bangin' around I did out there.

The plastic hose fell apart in his gloved hand. Paul felt it crumble, breaking into pieces at his touch.

He pulled his hand back as if it had been scalded. A ragged chunk of plastic was in the palm of his glove, part of the oxygen hose.

It can't be the bugs, he told himself. I didn't touch anything that was infected. Besides, we're still in daylight; it's too pissin' hot for the bugs to work.

Yet his insides trembled and burned.

What else could make a hose fall apart like that? Gotta be the bugs. Desperately, Paul tried to remember if he touched Wojo or anything out there when Wojo was cussing over the infected tractor. What difference does it make? he raged at himself. You're either infected with 'em or you're not.

How to tell?

He reached back again and pulled off another chunk of the plastic hose, about the size of his palm. Keeping one hand on the steering lever, he placed this new chunk of hosing on his thigh, alongside the first piece. They were roughly the same size. Satisfied, Paul placed the new piece atop the dashboard, in full sunlight. The first piece he tossed to the floor of the cab, deep in shadow.

Now we'll see.

Paul had to gear down the tractor as it began climbing the laborious winding trail that threaded through the ringwall mountains. The rounded, worn peaks averaged about ten thousand feet, but the trail notched through at least a thousand feet lower. Paul could see the tracks in the dust left by previous tractors. Like those old pidneer trails across the prairie, he thought. A hundred years later you could still see the ruts their wagons made in the ground.

Someday we'll h ve a monorail system to cross the ringwall, he told himself. Ormaybe we'll tunnel right through the mountains. Connect the crater floor with Mare Nubium. Someday.

For now, he had to steer the tractor slowly, carefully, up the gentle mountain slope. His tracks of earlier trips faded at the higher elevation, where there was little dust to register them. The rock surface was bare and slick here, almost glassy. Paul geared down again to maintain traction.

It took more than an hour, but at last he reached the crest of the mountains. Peering over the front of his tractor, Paul could see the cluster of humps in the crater's floor that marked the buried shelters of Moonbase.

Automatically he pressed down the accelerator. The tractor surged forward. But then Paul looked down on the floor at the piece of hosing lying in the cold shade.

He stomped on the brake. The tractor slewed slightly as it ground to a stop. With trembling hands Paul reached down and picked up the scrap of plastic. He placed it alongside the other piece, still in sunlight on the dashboard.

The piece from the floor was less than half its original size.

They're here! In the tractor!

He leaned down and pawed at his dust-caked leggings. The outer fabric of his surface suit was already eaten through. His boots, too. Paul could see the metal mesh layer that underlay the fabric.

They can't get through the metal if they're designed to eat carbon molecules, he told himself. Yeah? They got through the metal in Wojo's suit Must be different kinds. Different kinds.

He wanted to run. He felt unclean, infected, his skin crawling and his heart pounding so loud he could hear it in his helmet earphones.

And suddenly the enormity of it hit him. I'm going to die! Even if I get to Moonbase, I'll just be carrying the damned bugs with me. They'll infect the whole base, tear apart everything. Kill everybody.

That's what Greg's been after, all along! Not just me, but everything I stand for. He wants to wipe out Moonbase altogether!

Paul sat there inside his failing suit, blinking at the vision of Moonbase, everything he had worked for, everything he wanted, being utterly destroyed.

Strangely, the realization calmed him. He knew what he had to do now. There were no other options, no excuses, no escape clauses. It was finished.

At least I'm close enough to reach them with the suit radio, he thought.

Jinny Anson was at the communications desk when he called in.

"We'll send a team up to get you!" she said when Paul told her where he was.

"No!" he snapped. "I'm infested with nanobugs and you can't run the risk of bringing them into the base. They'll kill all of you."

"But what can we do? We can't just leave you out there. "You'll...' Jinny's normally chipper voice faltered, went silent.

"It's too late to do anything for me. Call Kris Cardenas in the San Jose division and get her to come up here and personally lead a decontamination team to clean up this mess."

"But what about you?"

Paul said, "Get my wife on the line for me. Private link. No eavesdropping."

Paul could not see Joanna's face, but he pictured it in his mind. She was beautiful. Whether she loved him or not didn't matter now. Whether she placed Greg before her husband didn't matter, either. Not any more.

"Where are you, Paul?" her voice asked. "Why can't we establish a visual?"

"I'm out in a tractor, at the summit of the ringwall."

He waited for her reply. "You're on your way back to the base, then?"

"I was," Paul answered. "BurI'm not going to make it"

The three seconds stretched, sketched. Then, "What do you mean? What are you talking about? How long can you stay outside?"

"For the rest of my life," he said. "The nanobugs are in my suit. They stopped their activity while I was in sunshine, it was too hot for them. But they must've chomped away on my suit while I was in the tempo and I can't bring them into the base; they'll eat up everything."

Joanna was already talking before he finished, "You can't just stay out there until you run out of air! They've got to get you, save you!"

"There's no way to do that," Paul said. "If I go down to the base I'll be killing everybody there."

"No, Paul! No!"