A blinking red dot showed up on the wall screen, halfway down the gray line marking the vent running atop tunnel three.

Zimmerman, sitting on one of the little wheeled console chairs like a walrus perched on a beach ball, pointed and asked, "That is him?"

"That's him," Anson replied.

"Can we speak with him?"

"He's got a pocket phone," she said. "He'll call in when he hits the first partition."

Joanna stared at the blinking red dot as it moved slowly along the gray line. Brudnoy stood beside her and put an arm around her shoulders. She leaned against him, grateful for the support.

Roger Deems unconsciously gnawed on a fingernail as the eight others-three women among them-filed into the security office. Just my luck, Deems thought, to be tapped for the security job this month. The others looked equally unhappy.

The security assignment was rotated among the long-time Lunatics. Usually the job required nothing more than keeping the base's surveillance cameras working. Drugs were a minor problem, but the long-timers usually policed themselves pretty well and kept the short-timers under control. The still that produced rocket juice was an open secret and seldom made problems for anyone. The toughest moment Deems could remember had been when two short-timers got into a fistfight in The Cave over a woman they both coveted. By the time that month's security chief had arrived on the scene, like the sheriff in an old west barroom brawl, the other Lunatics had already ended the fight simply by dousing the combatants with all the fruit juice they could grab from the dispensers. Wet and sticky, the two young men felt foolish and embarrassed. Wyatt Earp was not really needed.

Deems had been at his desk, performing a routine check of the surveillance cameras, when the automatic emergency announcement blared from the overhead speakers. The sound of the airtight hatches slamming shut all along the tunnel startled him, but he didn't get too worried until Jinny Anson's voice came on the speakers and ordered everyone to stay put, then ended with an ominous, "THIS IS NOT A DRILL."

Before Deems could get out of his desk chair Anson was on the phone, telling him tightly what had happened and what she expected him to accomplish. Deems swallowed twice to keep down the bitter bile that was suddenly burning its way up his throat, nodded once to Anson, and got busy. He punched into the loudspeaker system, startled to hear his own voice booming out in the tunnel as he said: "THIS IS THE SECURITY CHIEF. WE NEED VOLUNTEERS TO HELP CLEAR UP THIS EMERGENCY. ANYBODY IN TUNNEL TWO WHO ISN'T INVOLVED IN LIFE SUPPORT WORK AND DOESN'T HAVE TO GET PAST ONE OF THE CLOSED HATCHES, REPORT TO THE SECURITY OFFICE RIGHT AWAY.".

Volunteers. Deems almost laughed. Anybody who could reach the security office without going through one of the closed hatches was a volunteer. By definition.

Now the three women and five men stood crowded, worried and uncertain before his desk.

"The base director's locked himself in the EVC and is threatening to cut off our air," Deems said to the assembled 'volunteers," without preamble.

They gasped, shocked.

"We need to open the EVC's hatch," he went on, running a hand through his thinning hair, "and we don't have time for prebreathing."

"Whaddaya mean, "we?" Why do we hafta do it?"

"Yeah, aren't there specialists for a problem like this?"

"Like who?" Deems asked, trying hard to scowl at them.

No one had an answer.

"Listen," he said, leaning back in his chair and folding his arms over his chest, "we can sit here on our rumps and let the cuckoo sonofabitch choke off our air or we can try to do something about it. Which is it gonna be?"

"You mean we need to get into suits?"

"It's that bad?"

"Air pressure in tunnel four is 'way down, unbreathable," said Deems, actually beginning to enjoy the feeling of authority, "and the pressure's dropping in tunnel three."

"Christ! My wife's in three!"

Deems raised a chubby hand. "Don't panic. We've already got safety people evacuating three. She'll be okay."

"But we have to get into suits?" one of the women asked, not certain she had heard him correctly.

"That's right. No time for prebreathing, either."

"Isn't that dangerous?"

"Not if we do it right," said Deems. "We're going to the suit rack at the end of this tunnel and purge a half-dozen backpack tanks. Get rid of the low-pressure mix that's in 'em and refill them with regular base air. Then you won't need prebreathing and there's no danger of the bends."

"But if you pump up the suits to room-normal pressure they'll get so stiff we won't be able to move in them," said one of the men. Deems recognized him as an engineer from the mining group.

"You won't have to do any delicate work," he countered. "Just set up a laser torch to burn through the hatch."

The engineer looked dubious and muttered something too low for Deems to catch.

"But we've gotta move fast," Deems said, starting to feel like a real leader. "No time to waste. We've gotta get into the EVC before he knocks out all the pumps and recyclers."

"Isn't there any other way to get to the EVC?"

They don't like this, Deems could tell by looking at their faces. Not any of it. Can't say I blame them.

"Doug Stavenger is working his way through the old plasma vents," he said, "but we don't know if he can make it all the way to the EVC or not. In the meantime, we gotta get that locked hatch open."

"Wait a minute," said one of the engineers. "If the pressure's down in tunnel four and we burn through the hatch, won't that blow the air out of the EVC?"

"Right"

"And anybody in there gets killed."

"Most likely."

"Then what about Stavenger? What if he's in there when we blow the hatch?"

Deems shrugged. "We'll carry extra suits and try to get them on all three of the people in there before decompression get them."

"Fat chance," grumbled the engineer.

Deems knew he was right.

"Shouldn't we be taking the recyclers apart?" Melissa asked. Her arms hurt from exertion and she could feel blisters welling up painfully on the palms of her hands.

Greg snorted impatiently, kneeling over one of the pumps. "What good's the recycling equipment if the pumps aren't moving fresh air? Kill the pumps and you kill the people."

He seemed calmer now. Methodical. When they had first burst into the EVC Greg was frenzied, wild-eyed. Now he worked with the deliberate, meticulous care of a man who was totally dedicated to his task. He's really going to do it, Melissa said to herself for the hundredth time. He's going to kill them all. He's going to kill himself. He's going to kill me.

For the first time, she realized that there was no way to stop Greg. If she tried to interfere with his dismantling of the pumps, he would calmly brain her with one of the wrenches.

She shuddered.

"Haven't heard that booming noise again," Greg said absently as he worked, head bent over the inner works of the pump.

"No," said Melissa. "It's stopped."

"What do you think they're doing, outside?"

"I don't know," she said. "Getting into spacesuits, maybe?"

Greg laughed. "Fat lot of good it'll do them. There aren't enough to go around. Oh, I suppose my mother and her little circle of sycophants are in suits. But the others-no."

"Maybe they're calling for help."

Greg looked up at her. His face was smeared with grime, but he smiled brightly at Melissa. "I'm sure they are. They must be screaming for help. But the quickest any help can come from Earth is six hours or more, and that's only if they have an LTV all ready to go and it's programmed for a high-energy boost."

"They could be calling to the other bases here on the Moon, couldn't they?"

"My mother, ask Yamagata or the Europeans for help? She'd sooner die."

"You don't really believe that."

His dark eyes snapped at her. "Don't tell me what I believe! If she asked Yamagata or the Europeans for help, they'd end up owning Moonbase. She'd never do that. She wouldn't even think of it."

"But that's better than dying, isn't it?"

Greg pulled a section of pipe away from the dismantled pump and let it drop to the rock floor with a clang. "Besides, what could anybody do to help her? Before anybody can break through the hatch to get to us, everybody out there'll be dead."

Melissa paced back and forth along the narrow walkway between pumps, arms folded across her chest, massaging her aching muscles.

"They must be doing something," she said.

Greg snorted disdainfully. "If I know my mother, she's spending her last moments writing me out of her will."

Doug's sneeze rang along the length of the metal-walled vent like a raucous gong. The dust was filling his nose, choking his throat whenever he inadvertently opened his mouth. The vent was big enough for him to crawl on his hands and knees, but still the dust floated languidly up to his face with every step he took.

How on Earth could dust get into these closed vents? With a shake of his head he reminded himself that he wasn't on Earth and lunar dust got into everything, its burnt-gunpowder smell was as common in Moonbase as the odor of frying oil in a hamburger joint back Earthside.

I wonder what the nanomachines are doing with the dust particles that get down to my lungs, he asked himself. Despite the sneezing and coughing, he seemed to be breathing well enough.

He had passed three partitions. Two of them had opened up on the electrical signal from the control center, when Doug had phoned Anson. The third refused to budge, and Doug had to drill off its hinges, which were caked solid with lunar dust.

The partitions had been set up like valves in the blood stream, to flip open in one direction only, letting fumes flow outward toward the vacuum outside the base, but sealing firmly shut once the outward-pushing pressure dropped.

As long as the last seal holds, the one at the end of the vent, where it opens out at the face of the mountain, as long as that one holds the vent will hold air for me to breathe, Doug told himself.

Then a sudden thought struck him. Is there a backup set of controls in the EVC? Could Greg pop the outside hatch open and blow all the air out? And me with it?

No, he told himself. Greg doesn't know I'm coming along the vent, so even if there are backup controls he won't know to use them. It's not possible.

He hoped he was right In the thin beam of his penlight he saw that the vent ended in a T-shaped intersection up ahead. That's the junction with the main trunk, he knew. I'm at the end of tunnel four; the EVC is only a few dozen yards away.

He fished the phone out of his pocket again, flicked it on, and said softly, I'm at the juncture with the main trunk."

The comm tech's voice said, "Hold one."

Then Anson came on. "Okay. We've got an emergency team in suits ready to start burning open the hatch."

"In suits?" Doug blurted, startled. "But they haven't had enough time-"

"They're breathing regular air at base pressure."

"Oh. Okay."

"Are you ready to pry open the access cover in the EVC?" Anson demanded.

"Yes," Doug said. "In about two minutes."

"Okay. I'll start the team working on the hatch. That oughtta draw their full attention."

"Right."

"They've got a spare suit with them, for you."

"Only one?"

"They've got two more, but I told them to be sure they slap one on you before they do anything else."

"Okay. Thanks."

Doug stuffed the phone back in his pocket, thinking, Once they blow that hatch all the air's going to rush out of the EVC. Explosive decompression. A spacesuit won't help unless they can get it on before your blood boils and your eyes pop out of your head.

He inched his way to the final access panel. I've got to stop Greg before they blow that hatch, he told himself.

MAIN GARAGE.

"There's a body here!"

Deems had to bend over to see the spacesuited figure slumped on the main garage's rock floor halfway between the hatches to tunnel four and tunnel three.

Several of the team gathered around the fallen figure, bending stiffly in their overpressured suits.

"He's unconscious."

"I think it's a woman."

"If whoever it is got into that suit without prebreathing, he's got the bends. Or she."

Just what we need! Deems growled to himself. Some stupid shit who didn't get in to safety in time.

Pointing to the man closest to him, he said, "Drag him inside tunnel two and call the medics. Then get your butt back out here right away. We're gonna need every pair of hands we've got."

It felt spooky as his eight men and women waddled cumbersomely through the main garage to the closed hatch that was the entrance to tunnel four. The garage was usually bustling and noisy with tractors being repaired, technicians yelling back and forth, music from individual disk players wailing over the clang and clamor.