Bianca had screened off this unused part of the main garage to serve as her practice hall. It was as far away from everything-and everyone-else as it could be, a good hundred meters from the nearest airlock.

There was definitely a wind surging through the main garage. She could see dust swirling along the floor. Somehow one of the airlocks to the outside must have been opened and the air was rushing out into the vacuum. A pang of fear shook her. I'll never get to one of the tunnel hatches in time!

A rack of six spacesuits stood a few meters away, hanging like empty suits of armor against the rock wall. There were racks like this spotted throughout the garage, standing ready against a possible emergency.

Bianca dashed to the nearest suit, ducked under its torso and wormed her way into it. As soon as her hands wiggled into the gloves attached to the arm cuffs, she reached overhead and grabbed the helmet, desperately hoping that the backpack's tanks were filled with breathable air. She clapped the helmet down on the neck ring and sealed it, then took a deep breath. The seal mechanism automatically activated the air flow.

Okay, she told herself shakily. The gasket around the waist of the torso shell will hold your air; you've got a couple of minutes to get into the leggings. It was awkward bending inside the hard shell of the suit's torso, but she ripped off her ballet slippers and got into the leggings faster than she had ever done before. Then she sat on the floor and pulled on the boots.

I did it! Bianca exulted. I got into the suit. Then she remembered that if she stayed in the suit for more than a few minutes she would get decompression sickness: the bends.

Greg had dragged Melissa from his office, down the tunnel toward the rear of the base.

"You want to destroy everything?" he had screamed at her. I'll show you how to wipe them all out! All of them!"

Melissa tried to keep up with him but her legs wouldn't work right in the low lunar gravity. She stumbled, flailed her free arm to regain her balance, then tripped again and fell to the floor. Greg hauled her along, skidding and scraping on the cold rock floor.

Two women and a young man, all in the olive green coveralls of the mining division, rushed up the tunnel toward them.

"What's the matter?" one of the women asked. "What's going on?"

"Get out of my way!" Greg roared. "Get out! Now! Leave us alone!"

The two women glanced at Melissa, sitting on the tunnel floor with her legs drawn up, glaring up at them.

"I'm the base director," Greg bellowed, banging the nametag on his chest with his free hand. "Get out of my goddamned way."

"Call security," said the young man. "Let them take care of it."

They hesitated a moment longer, staring at Greg's wild-eyed expression and Melissa, her arm still hanging in his grasp.

"Come on," said the young man. The three of them hurried up the tunnel.

"Assholes," Greg muttered after them.

Melissa yanked her wrist free of Greg's grasp. He turned on her, hand raised to strike.

I'll help you," she said, climbing slowly to her feet 'You don't have to drag me. I'll go with you willingly."

"You bet you will," Greg said. And he started down the tunnel again.

"Where are we going?" Melissa asked, trying to keep up with him without stumbling again.

"EVC," he muttered.

"What?"

"Environmental control center. The air pumps."

Breathlessly, Melissa answered, "Good."

Greg felt lightheaded, almost giddy, as he hurried down the tunnel. Don't run, he warned himself. You might trip yourself and fall. You don't want to look foolish in front of Melissa. He thought about the veteran Lunatics he had seen taking yards-long strides in the gentle gravity, soaring along like ballet dancers. I'll show those wiseasses, he thought I'll show them all. Let's see how far they can jump when there's no air left to breathe.

For the first time in his life Greg felt free, totally, absolutely free. It didn't matter what anyone thought or said or did. This is the end of it all. At last it'll all be over with, finished. The end of everything. No more fear. All my worries are behind me now.

To Melissa, this tunnel seemed longer than the others. As she struggled to keep up with Greg, she saw that they had passed the area where laboratories and offices lined the tunnel on both sides. Now the doors were farther apart and the labels on them proclaimed MAINTENAISjCE STORES and ELECTRONICS SPARES.

At the end of the tunnel was a dull metal hatch with an electronic security pad alongside it.

"Rank has its privileges," Greg said, almost giggling as he tapped the keyboard with his index finger. "All the base director has to do to open any hatch, anywhere, is punch in his personal code."

Greg's eyes were aglow. Melissa thought he looked-happy. I've freed him, she said to herself. I've freed us both.

The hatch clicked but did not open. Greg grasped its metal wheel, gave it half a turn and then pushed.

Inside was a shadowy cavem that throbbed with the sound of pumps.

As Greg, suddenly solicitous, helped Melissa over the hatch's coaming, he explained, "All the base's air supply is routed through here. That's the recycling equipment...' He pointed to a clump of bulky metal shapes connected by a maze of piping. "We'll take care of them later."

He pushed the hatch shut, then spun its wheel, locking it.

"Find a tool box," he ordered Melissa. "There's got to be tools stashed here someplace."

"What about those lockers?'1 She pointed to the row of metal lockers a few feet down the wall from the hatch.

"Right' said Greg. He yanked the lockers open, one after the other, and slammed each door shut again with a disgusted clang. "Emergency space suits, emergency oxygen tanks, extra coveralls-where "do they keep the fucking tools?' His roar echoed off the bare rock walls.

"Here." Melissa called from a workbench on the other side of the hatch.

Greg rushed to her. "Right!" He yanked open the metal boxes lining the back of the workbench and lifted out a heavy wrench. "Just what I need."

Grinning madly, he went back to the hatch and lifted the back cover off the security pad. Then, raising the wrench over his head like a spear, he jammed it into the electronic works of the hatch's security pad. Sparks crackled, throwing blue-white highlights against his grimacing face.

"There," Greg said triumphantly. Then he jammed the wrench into the hatch's wheel, to prevent it from being turned. "Now if they want to get in here they'll have to blast."

He whirled around, eyes blazing. Melissa felt her heart thundering beneath her ribs. We're going to do it! she said to herself. We're going to tear it all down! We're going to put an end to all of it, at last!

There was a computer at the end of the workbench. Greg strode to it, bending over the keyboard.

"One system at a time," he muttered. "First the lights."

The computer screen lit up. Greg worked the keyboard, fingers moving in staccato rhythm. Melissa thought the sparse overhead lights flickered, but the lighting was so dim in this cavern that she couldn't be sure.

"Damn! The backup nuke conies on-line automatically and there's no way to shut it down unless the solar farms come back on."

He pecked at the keyboard again, harder. "Shit," he muttered. "Shit, shit, shit."

"You can't do it?" Melissa asked, looking at the incomprehensible alphanumerics scrolling up the display screen.

"I can do it," Greg growled. "I just can't do it through the damnable computer. Too many redundancies and backups."

"Then what-"

"The main airlock!" Greg crowed. "I can open the main airlock long enough to blow all the air out of the garage! Emergency decontamination procedure. Look!"

Melissa saw another jumble of symbols on the computer screen, but overhead loudspeakers immediately blared out a warning that echoed through the big cavern.

"That's just a start!" Greg shouted.

He ran back to the workbench, picked up another wrench, and waved it in the air. "I'm going to wipe them all out!I can do it! Watch me!"

Melissa followed him down the narrow walkway between man-tall metal shapes that throbbed and chugged ceaselessly.

"I don't need the compiler system," Greg railed, banging his wrench angrily on the metal domes of the pumps as he passed them, making the cavern ring. "I don't need the fucking computer! I'll do it the hard way!"

"Do what?" Melissa asked.

Instead of answering her, he turned and pointed back to the workbench. "Get every tool you can carry. Bring them to me. Now!"

She scurried to obey, staggering slightly in the unaccustomed gravity, righting her balance by leaning against the cold metal pumps.

She went to the toolbox they had already opened and lifted out an assortment of wrenches, pliers and screwdrivers. By the time she got back to Greg he had already twisted off two of the four bolts holding down the domed top of one of the pumps.

"It all gets down to plumbing," Greg mumbled as he worked furiously. "All the high technology of this base depends on pipes that carry either air or water."

"You're going to break the pumps?"

Greg looked up at her, a grease stain already smeared across his forehead. I'm going to cut off their air supply. Let them choke to death on their own fumes."

"Us too?" she asked.

He laughed. "Of course, us too. We'll die together, Melissa. You'll like that, won't you?"

"I was in love with you," she said.

"No greater love has any man," Greg babbled as he yanked at the bolts of the pump, "than he lays down his life for his ex-lover."

She dropped to her knees next to him. "Kill them all," she whispered urgently. "But be sure to kill us, too."

"We'll die," Greg said triumphantly. "We'll all die!"

CONTROL CENTER.

Doug flew down the tunnel, his feet barely touching the ground, leaping the distance between one closed airtight hatch and the next in a few long, loping lunar strides.

Jinny Anson was already in the control center when Doug got there. So was his mother and Lev Brudnoy.

"They're in the EVC, affl right," Anson was saying, pointing at the big electronic wall map of the base. "Sonofabitch blew out the garage and now the oxygen partial pressure in tunnel four is below safe level."

"How could he do that?" Joanna asked, wide-eyed.

Still scowling at the wall map, Anson replied, "He just opened the main airlock. All the air in the garage got sucked out into the vacuum."

"But how-"

"There's an emergency procedure in the computer controls," Anson answered impatiently, "so we can clear the garage of toxins or radioactives or any other crap in a hurry."

"Was anyone in the garage?"

"Of course! We're counting heads now, making sure everybody got out okay."

"What about tunnel four?" Doug asked. "That's the tunnel that leads into the EVC, isn't it?"

"Yeah, right. He must've shut down the pumps, I guess. Or maybe turned off the air-circulating fans. It doesn't take much."

"What is he trying to do?" Brudnoy asked.

"Commit suicide," Joanna replied without an instant's hesitation.

"And take all of us with hint?" Anson almost snarled the words.

Joanna nodded silently.

Doug asked, "Has anybody been able to make contact with him?"

Anson shook her head. "He doesn't answer, not even the paging system. And he must've knocked out the surveillance cameras somehow, we can't get a picture from inside theEVC."

"Damn!"

Doug saw that the consoles were fully manned; tight-lipped technicians sat at the monitor screens, headsets clamped to their ears, fingers running over their keyboards as they checked every system in Moonbase.

In the control center's air of quiet frenzy, Anson had naturally, automatically taken charge.

"He's trying to knock out the whole base," she said, thinking aloud. "Already blown out the garage and tunnel four's down below safe minimums. It's only a matter of time before he gets the rest of us."

"What can we do to stop him?" Joanna asked, sounding a bit frantic.

"First things first," said Anson. Turning, she marched to one of the consoles and spoke to the technician seated there. "Activate all the emergency air filtration systems. And get a squad of safety people to manually check them."

Doug saw the question in his mother's eyes. "Backup systems," he explained, "to filter the carbon dioxide out of the air. Even if Greg shuts down the main recycling equipment, the backups will keep our air breathable."

"For how long?" Joanna asked.

Brudnoy looked at her with sad eyes. "A few hours," he said softly. "At most, a few hours."

"Shouldn't we get everyone into spacesuits, then?" Joanna suggested.

"There aren't enough suits for everyone," Brudnoy countered.