Paul was in the company helicopter heading back to San Francisco International Airport when his pocket phone beeped.

It was Melissa. “Delta’s flight’s been cancelled,” she said, “and there’s nothing connecting to Savannah until late tonight. Can I ride back with you?”

“Sure,” Paul said, knowing it was a mistake, not knowing how to say no without feeling like a jerk.

Melissa was waiting for him in the hangar where his twin-engined jet was sheltered. The same plane in which he and Joanna had made love for the first time. Melissa was standing beside the plane, looking slightly forlorn in a baggy pair of tan slacks and a light sweater that hung loosely on her.

“Sorry to impose on you,” she said as soon as Paul got to within arm’s reach. I’d have to fly the redeye to Atlanta and then make a connection at six tomorrow morning, otherwise.”

“It’s okay,” Paul said. Last night they had been in bed together. But that was last night.

Melissa picked up her single garment bag. “I know I look a mess. This is my airline outfit. It’s for comfort, not looks.”

He made a smile for her. “You look fine, kid.

As he walked toward the plane beside Melissa, Paul remembered his elderly grandfather on the day the news broke that the first black president of the United States had been caught in the sack with a woman who was not his wife.

His grandfather had shaken his head mournfully. “See the trouble a man’s cock can get him into?”

Yeah, I see, Gramps. But Seeing ain’t the same thing as doing.

Paul let Melissa sit in the co-pilot’s seat as he slipped on the headset and checked out the plane’s instruments. She did not say a word to him as he taxied out to the runway, got clearance for takeoff, and then shoved the throttles forward.

The engines howled joyfully and the plane surged down the runway, faster, faster, the ground blurring as Paul watched the digital airspeed display, then pulled back with an artist’s delicate touch to rotate the nose wheel off the concrete. The plane seemed to leap into the air and Paul’s heart soared with it.

Once they cleared the airport traffic and Paul put the twin-jet on course eastward, he slipped his earphones down around his neck and turned to Melissa.

“Too bad there’s no Clippership service to Savannah,” he said.

“When will we get there?”

“Eleven-thirty, eastern time, the way things look now. We’ll have to make a pit stop in Amarillo. Gas up.”

Melissa nodded. “Beats the redeye.”

For a while neither of them said anything. Paul watched the shadows lengthening below as they flew over the mountains with the sun setting behind them.

“Lake Tahoe,” he said.

“Uh-huh.”

Time went by in silence. Then he pointed out the Grand Canyon, barely visible off in the distance in the twilight haze.

Melissa stared out the window on her side of the cockpit until a cloud bank obscured the ground altogether.

Finally, Paul said hesitantly, “About last night—”

Melissa turned sharply toward him. “Forget it,” she said.

“Forget it?”

“It never happened.”

Paul felt puzzled. “What d’you mean?”

“You’re a married man and you’re worried I’m going to shoot my mouth off to Greg or somebody. Well, don’t worry about it.”

“That’s not what I meant.”

“Isn’t it?”

“Shit, Mel, I wasn’t thinking you were a spy for Greg.”

“The hell you weren’t.”

“You told me you two had broken up.”

“Yes. That’s right.”

Paul’s befuddlement deepened. Melissa seemed irritable, almost angry.

“Look,” he said. “I’m sorry about last night. I shouldn’t have done it. I am a married man and—”

“Oh, Paul, it’s not your fault. I…” She seemed to want to say more, but stopped.

Paul didn’t know what to say. If anything. It was a stupid thing to do, he told himself. If Joanna finds out I’ll have hurt her just as bad as Gregory hurt her in the past.

“Do you know why Greg and I broke up?” Melissa asked, her voice so low Paul had to strain to hear her over the muted rumbling of the engines.

“You said it was because of Joanna.”

Melissa shook her head slowly. “That’s only part of it. I mentioned the magic word, and that drove him off the deep end.”

“The magic word?”

“Baby.”

Paul wasn’t certain he had heard her correctly.

“I told Greg that I wanted his baby,” Melissa said sorrowfully. “I told him that when a man and a woman love each other they make a baby together.”

“He didn’t like the idea.”

“I thought he was going to punch me out.”

“If he ever lays a hand on you—”

Melissa silenced Paul by laying a slender finger on his lips. “I can take care of myself,” she said. “You’ve got a wife to think about. You can’t go around fighting my battles.”

But Paul pictured Greg hitting Melissa. Just like the spoiled sonofabitch, he thought. He doesn’t love anybody except himself. If he ever touches her I’ll punch out his lights, but good.

After they stretched their legs in Amarillo and took off again, Melissa curled up in one of the capacious reclining seats in the plane’s cabin and fell asleep. Paul put the plane on autopilot, but flayed in the cockpit, awake, his mind churning with thoughts of Greg and Melissa and Joanna and the nanomachines that could make Moonbase a going proposition if only he could hammer the idea through the board of directors. But Greg was going to use the next meeting to accuse him of murder, or at least fornication. How can he attack me without attacking his mother? Then Paul realized that Greg was so furious with blind hate that he wanted to hurt Joanna, punish her for falling in love with a black man.

It was almost midnight when Paul finally put the twin-jet down on the company’s airstrip, a few miles from Savannah. He was tired, drained physically and emotionally. Gratefully, he saw that the limo was there at the apron in front of the hangar, waiting for him.

Paul helped Melissa down the little metal ladder to the concrete of the apron. When he turned back toward the limousine, he saw that Joanna was standing beside it, staring at them.

Do I have enough oxygen to make it? Paul asked himself that question again and again as he struggled across the rocky undulating lunar plain, trying to make up for the time and distance he had lost by straying so far off course.

He pushed himself harder. “Gotta get smokin’ now,” he told himself. “Gotta get there before the oxy runs out.”

Somewhere in the back of his mind he remembered an equation that showed how oxygen consumption is related to the amount of physical work the body is doing. From some aerobics class he had taken back when he was in astronaut training, a thousand years ago. Shaking his head inside his helmet, Paul tried to forget about the equation. Just keep pumping along, he told himself. Go, go, go.

At least he had the GPS signal to keep him company. Cheerful little chirp in his earphones, almost like a songbird but nowhere near as melodious. Just a monotonous steady set of peeps, repeating over and over again.

Hey, don’t knock it, he told himself. Long as you can hear that boring little song you’re on the right track. You can listen to Wynton Marsalis some other time.

Through his dust-smeared visor Paul could make out the bulky shape of a massive boulder rising up on the horizon ahead of him, like a ship coming in from some far-off land. Boulder big as a house, Paul thought. As he got closer to it he saw that it was as big as a shopping mall.

Got to go around it. Damn! Pissin’ chunk of rock’s gonna force me ten-twenty minutes outta my way.

Squinting through his dust-covered visor, Paul saw that the huge boulder was pitted and rough, with a fairly flat top. Maybe I can climb over it. Be faster than walking all the way around it.