… THE SUN SHIELDS WERE nearly closed when Spence stepped into the garden. The slanting bands of golden light falling through the trees resembled a kind of tropical aurora which flushed everything with heightened color. This was Spence's favorite time to come here-just before the shields closed and the garden received its nocturnal rest.

He hurried along to the center of the garden and the benches on the greensward. As he had hoped, the benches were empty; not another soul was to be seen anywhere. He settled himself on the last bench to wait. The only thing missing is mosquitoes, thought Spence as he listened to the racking squawks of one of Central Park's half-dozen macaws.

He closed his eyes and breathed the humid air deep into his lungs, tilting his head back to rest on the bench. He was still in this attitude, eyes closed, head thrown back, when Ari found him.

"I know I haven't kept you waiting that long!" she said. "How dare you pretend to sleep."

Spence's head snapped upright as his eyes flew open. He jumped to his feet. "I didn't hear you come up." He looked at her and stood uncertainly, gazing intently at her fair face, even lovelier in the soft golden light of the garden. He tried to read her feelings in her eyes, but could not.

"Ari," he said, after an awkward moment, "thanks for coming. After what I did you had every right to refuse, and I wouldn't have blamed you."

She did not make the moment easier for him, but stood there looking at him implacably.

"I am sorry. I… I treated you terribly." His eyes sought hers and his voice became hushed. "I've never asked another person to forgive me, but I'm asking you now. Please, forgive me."

The smile that transformed her face came like the dawn to his long, dark night of despair. All the way to the garden he had tortured himself with six kinds of fear and doubt as to the outcome of their meeting. Her voice over the ComCen speaker had been icily polite, giving away nothing that he could use to bolster his sinking ego. But her smile banished all his dark thoughts.

"Oh, Spence, I've been so worried about you. Furious, too, mind you. But more worried than mad."

"I acted like an ass. Running out of the cafe that way-I don't know what I was thinking of. I'm sorry…"

"You're forgiven. Now, what is so urgent and secret?"

He drew her to the bench and sat her down. He looked around him as if he expected spies to be lurking in the shrubbery. She could see that his face was flushed with excitement. His slightly wild-eyed look was creeping over him again. She bit her lip. "What is it, Spencer?" 'I have proof that I'm not going crazy."

… YOU'RE GOING TO HAVE to trust somebody." Ari's voice was firm. "You can't go it alone."

They were sitting in her father's reading room. A plate of sandwiches sat untouched on the low table in front of them. Spence stared at the walled ranks of books as if he might find a title among them that would tell him what to say next.

"I need time to sort this out," he said at length. "There are too many pieces missing."

"I don't like it, Spence-this running away. It isn't safe."

He swung around to peer at her with a puzzled look. "It'll be all right," he said lamely. "I need to get away from here for a while, that's all."

"What makes you think that if someone is tampering with your experiment they would stop there? They could hurt you, Spence. For whatever reason, you could get hurt very badly."

He had no answer for that. The same thing had crossed his mind many times in the last few hours. "Ari, all I know is that if I stay I will be hurt. I've got to go someplace out of reach to figure this thing out."

There was a finality in his tone that did not invite further discussion. Ari sat with her hands in her lap, legs drawn up beneath her. She studied her clasped hands and said, "I'll miss you."

He smiled. "I'll miss you, too. Believe me, if I thought there was another way, I'd take it." He drew a deep breath. "I won't be gone long; you'll see. I'll be back in no time at all."

"I don't call three-and-a-half months no time at all." She colored slightly and admitted, "I was just getting used to having you around. "

"We'll pick up right where we left off, I promise." He looked at her steadily and said, "If I stayed, you wouldn't want me around. It would be more of the same. Worse maybe."

"You're probably right. Perhaps it is better this way." She turned her head away quickly. He moved closer and touched her shoulder tentatively.

"Are you crying?"

"No!" she sniffed. "I'm allergic to good-byes."

Spence put his hand to her chin and turned her face toward him. A moist trail glistened on her cheek where a tear had fallen. He wiped away the spot and bent his head and kissed her very gently.

"That's for missing me," he said shyly.

Ari smiled and sniffed, rubbing the heel of her hand across her eyes. "The secret's out now, isn't it?" She looked at him again and he felt his insides turning to warm jelly. "Be very careful, Spencer. Don't let anything happen to you."

"I won't…," he managed to croak.

"Spence, I will pray for you every day." She folded her hands unconsciously. "I have been praying for you ever since we met."

He felt as if he had just stepped into a warm shower. His skin tingled with a strange excitement and his heart tugged within him. He wished that he could say that he would pray for her, too. But he knew that such a statement would ring false. It would cheapen her sincere belief. And though Spence himself had no such beliefs, he did not see any good reason to trample on hers.

"Thank you, Ari," he said at last. "No one has ever said that to me before."

They sat for a long time in silence. Finally, he rose uneasily to his feet and said, "I guess I'd better go. I've a lot to do if I'm going to leave tomorrow night."

"Am I going to see you before you go?"

"I hope so. I'll come by here before I head down to the docking bay. Now you're sure-"

"Yes, you're cleared. And no one outside of Captain Kalnikov knows you're going."

"Good."

"But Spence, shouldn't you tell somebody? Someone should know."

"You know. Everyone else will find out after I'm gone."

Ari sighed. "All right, if that's the way you want it."

They moved to the portal and Spence pressed the access plate. "I'll see you tomorrow," he said, ducking quickly outside.

"Good night, Spencer." Ari waved. He waved back and the closing panel broke the spell between them.

He hurried back to his quarters feeling like a cat burglar returning., after a night's work. A thousand details had to be attended to before he climbed aboard the transport headed for Mars; between now and then he had precious little time to spare. He would need to work through the night. …

HE HAD JUST CLOSED the door to the vidphone booth at ComCen when the call came through. He sat down and leaned into the camera slightly, resting his elbows on the shelf before him. The flat, square screen flickered to life in quick bursts of blue light. He smiled when the red light above the screen came on.

"Spence, it's Kate. Are you surprised to see me?"

He had not expected to see his sister, and for a few seconds could only stare at the image on the screen. In fact, he had imagined so many emergencies which might have provoked the call that he was a little disappointed to see her.

"Your sister, Kate-remember?" She smiled nervously. "Kate, are you all right? Is everything all right?"

"I know I should have given you more warning. Yes, every thing's fine. No emergencies. You sound angry."

"It's just that it's in the middle of the night here-"

"I'm sorry. I forgot. It's three o'clock in the afternoon down here."