The three men spent the rest of the afternoon checking every square millimeter of the shelter. It was airtight. Radiation levels were well below minimums. Temperature hovered at twenty-five degrees Celsius.

They still had to use the tractor's communications gear to contact Moonbase and San Jose. There hadn't been enough capacity in the tractor to hold all the comm equipment that a shelter normally had, mainly because they had hauled the rocket hopper along with them.

Little more than a railed platform with a rocket motor beneath it, the hopper was a safety tactic, a hedge against danger. It could lift three men-and practically nothing else-as far as the next shelter, twenty miles away.

Paul was sitting on one of the bunks inside the shelter, sending the results of their checkout to San Jose, patching the link from his hand-held communicator through the tractor's comm unit. Kris Cardenas' image on the tiny screen was streaked with white hashes of snow. Suddenly it winked off altogether. Paul's portable went dead.

At that moment, Tinker came in through the airlock. He had gone outside to gather up his microwave detectors.

Sliding up the visor of his helmet, Tink said," Wojo''shaving some trouble with the tractor Annoyed and puzzled at his communicator's failure, Paul looked up at the astronomer. "What?"

"He's out there turning the vacuum blue," Tink said, not looking particularly worried. "Something's wrong with the tractor. I tried to give him some help, but I don't know enough about cryogenic motors."

A tendril of fear wormed along Paul's spine. "Maybe he needs a hand." He got up and went for his suit.

"I think he'll need more than applause," Tinker punned.

The suit still smelled ripe, but Paul barely noticed as he pulled it on, piece by piece. Tinker helped him into the backpack and checked all the connections.

"You are go for surface excursion," said Tink, patting the top of Paul's helmet. The standard line sounded strange, coming from him.

Paul powered up his suit radio as he stepped into the airlock. He could hear Wojo's fervent litany of methodical, dispassionate cursing.

"... slime sucking, pus eating, dung dripping misbegotten son of a promiscuous Albanian she-goat and a syphilitic refugee from a leper colony..."

"What's the matter, man?" Paul asked, loping across the dusty ground in the gliding long low-gravity strides of the experienced lunar worker.

"Would you believe," Wojo replied, still bent over the tractor's electric motor compartment, "that this miserable excuse of an electrician's wet dream is completely shorted out?"

Paul had to lean far over to see the motor, inside its insulated compartment. In the light of their two helmet lamps, the aluminum coils looked blackened; some of them appeared to be bent, as if they had been pulled apart "What in hell...?"

Wojo held up a length of narrow plastic tubing. "Seals are eaten through. Each and every blessed seal is leaking like a busted sieve. All the nitrogen coolant's evaporated."

"How could that happen?"

Wojo must have shaken his head inside his helmet. "Don't know how, but it must've happened while we were sleeping. Mother-lusting motor worked fine yesterday."

"And the back-up?"

"Same goddamned thing."

That was the first time Paul had ever heard Wojo actually resort to blasphemy, however mild. He must be really worked tip, Paul thought.

"Goodthing we brought the hopper," he said.

"Yeah," Wojo agreed.

But the hopper was useless, too. The tubing connecting its propellant tanks to the rocket's combustion chamber was eaten through.

"It looks like it's corroded," Paul said, completely puzzled. "Like an iron pipe that's been left underwater for years."

"It ain't iron and it hasn't been underwater," Wojo muttered. "This tubing is high-strength plastic and it looks like something's just chewed right through it."

Gobblers! Paul's knees went weak with the realization.

"Jesus," he moaned.

"What is it?"

"Put the tubing down!" Paul snapped. "Drop it!"

Wojo let it fall. The length of tubing tumbled slowly and bounced when it hit the ground.

"Get away from here. Move away!"

"What's the matter, boss?" Wojo asked, his voice more flustered than fearful. "What is it?"

"I'm not sure, but we-"

"Hey!" Wojo shouted. "I got a leak!"

"Where?" Paul reached for the pocket in the thigh of his suit, where patches were kept.

"I can't-' Wojo's voice cut off. He started coughing.

In the light of Earthglow Paul could see the fabric of Wojo's gloves rotting away, dissolving, melting. The inner lining of metal mesh was showing through on most of his fingers.

"Get into the shelter!" Paul yelled. "Run!"

Wojo stumbled for the airlock hatch as Paul stood between the tractor and the hopper, immobilized by fear and the realization of what was happening.

Gobblers. Somehow gobblers have been mixed in with the nanobugs. They're eating up anything with carbon molecules in them.

Wojo was two steps from the airlock hatch when he screamed and fell face-forward to the ground. He writhed as if something was eating him alive, his screams higher and higher until abruptly they stopped altogether and he became still.

"Wojo!" Paul yelled. "Wojo!"

The airlock hatch slid open and Tinker stepped out, fully suited.

"What the hell's going-"

He stopped and bent forward slightly to stare at Wojo, lying two paces before him.

"Did you handle any of the tubing from the tractor?" Paul shouted into his helmet microphone.

"What happened to Wojo?" Tinker started to bend down beside the fallen man.

"Get away from him!" Paul shrieked.

Tinker jerked back, staggered slightly and bumped against the open hatchway of the airlock.

Frantic, Paul demanded, "Did you handle anything from the tractor?"

"What're you talking about? What's happened to Wojo?"

"He's dead, dammit!"

"Dead?"

Paul felt as if he had stumbled into a leper colony. He didn't want to touch anything, get near anyone.

Forcing himself to be as calm as possible, he said to Tinker, "Something's gone wrong with the nanobugs. They've infected Wojo's suit and eaten away the insulation."

"His suit failed?" Tinker's voice went hollow with sudden fear.

The goddamned bugs are chewing up his body, Paul knew. But there was no sense scaring Tinker more than he had to.

"Did you handle anything from the tractor?" Paul asked again. "Or the hopper?"

Sounding confused, Tink said, "I looked over Wojo's shoulder-God, is he really dead?"

"Did you touch anything?"

"He... he showed me a piece of tubing that had broken down. I looked it over."

"Did you touch it?"

"Yes! Of course I touched it."

"Get back inside the shelter and get out of that damned suit as fast as you can," Paul commanded. "Shove the suit into the airlock and stay inside the shelter until I can get some help here."

"I don't understand," Tinker said.

"Your suit's infected with nanobugs that attack carbon-based molecules," Paul said, annoyed with the astronomer's obtuseness. "Now move!'

"Carbon-based molecules? That includes me!"

"Damned right! Get out of that fuckin' suit as fast as you can!"

Tinker ducked back through the airlock at last. Paul stood frozen with terror, staring at Wojo's fallen body. His spacesuit was disintegrating before his eyes. In the soft light from Earth overhead, Paul watched as the arms of Wojo's suit slowly disappeared, layer by layer: fabric, insulation, the neoprene gaslight bladder. They'll be down to his skin and flesh; like maggots.

Tinker's first scream turned Paul's blood cold. Tink either hadn't taken off his helmet, or he had left his suit radio on while he was getting out of the spacesuit. Either way, Paul heard him screaming and screaming and screaming. Wojo had died of decompression when the bugs had eaten through his suit. Tinker was devoured alive, screaming until his voice went hoarse.

Paul stood alone out on Mare Nubium, his two companions dead, the area infested with killing nanobugs, the nearest shelter twenty miles away.

Greg, he knew. Greg's done this. He's the only one who would even think of it Slipped a sampling of gobblers in with the assemblers. He's trying to murder me. He's killed Wojo and Tink. I'm next. If I let him.

SHELTER 19.

Paul was struggling with an invisible demon. He couldn't see it, but he could feel it clutching at his throat, tearing at his flesh. He thrashed madly, grappling with it, trying with every ounce of strength in him to push it away, to get it off him.

His eyes snapped open. Above him curved the rounded ceiling of Tempo 19. Air circulation fans hummed softly and a pump chugged faithfully in the background.

I'm safe, he told himself, lying in his sweaty coveralls on the bunk. I'm okay. For how long?

"Long enough," he said, his voice a grating, harsh rasp. Wincing when he put his weight on his right foot, he limped to the food freezer and microwave oven that comprised the shelter's galley. The sink was beside it. Paul took a plastic cup from the rack over it and filled it with water. He drank it down slowly; it was warm and flat and the best drink he had ever tasted. He savored it, relished it, gloried in the way it eased the sandpaper feeling in his throat.

He pulled out a plastic container of frozen soup and popped it into the microwave. Then he limped to the communications console and called Moonbase.

Impatiently he reported the deaths of Wojo and Tinker. The guy on comm duty quickly called the base's director, and Paul had to repeat the news to her.

"The nanomachines killed them?" her hard-bitten face radiated surprise, disbelief.

"And damned near killed me, too," Paul said wearily. "Now patch me through to Savannah. I want to talk to my wife."

"Just a minute," said the base director. "I need to know a lot-"

"Later," said Paul, putting iron into it. "I want to talk to my wife. Now. On a private link."

"Okay," the director said. I'll put together a team to go out there and get the bodies."

"No! Nobody goes anywhere near that site until I've had a talk with the San Jose troops. That whole area is quarantined as of now,"

The director's eyes went wide for a moment. Then she nodded. "Understood."

Paul was glad that Joanna was in her office at corporate headquarters. From the looks of the little urban park outside her window it must have been late afternoon.

She was smiling as her face appeared on the tabletop display screen before Paul, but her smile froze the instant she saw his haggard, bleary-eyed face.

"Paul, what's happened?"

He had spent twenty minutes setting up a direct laser link to Savannah. Anybody at Moonbase could tap into his transmission from the shelter, if they dared, but from Moonbase's laser to the receiver on the roof of the headquarters building, no one could eavesdrop.

"Greg tried to murder me," he said, then waited three seconds for the shock to register in her face.

"Greg? How...?"

"He put a mix of gobblers in with the nanobug assemblers. Two men were killed and he damned near got me."

"Gobblers?" Joanna echoed.

"Nanobugs that take molecules apart. Long-chain carbon molecules. Like spacesuit materials. Like human flesh."

Joanna gasped, "Oh no."

"There's a tractor outside this shelter. I'm going to ride back to Moonbase and then head home."

He could see the conflicting emotions battling within her. "What should I do? About Greg, I mean?"