Every night she came to him, and she taught him what she had been taught by her sisters, by the other men, and his joy intensified until he wondered how the others had stood it before him, how he could stand it.

In the afternoons he ran to the old house, where he was making her a pendant. It was the sun, two inches in diameter, made of clay. It had three coats of yellow paint, and he added a fourth. In the old house he read again the chapters on physiology, sexual responses, femininity, everything he could find that touched on his happiness in any way

She would say no one night soon, and he would give her the pendant to show he understood, and he would read to her. Poetry. Sonnets from Shakespeare or Wordsworth, something soft and romantic. And afterward he would teach her to play chess, and they would spend platonic evenings together learning all about each other.

Seventeen nights, he thought, waiting for her. Seventeen nights so far. The cover was over the window, his room was clean, ready. When his door opened and Andrew stood there, Mark jumped up in a panic.

“What’s wrong? Has something happened to Rose? What happened?”

“Come with me,” Andrew said sternly. Behind him one of his brothers watched.

“Tell me what’s wrong!” Mark yelled, and tried to run past them.

The doctors caught his arms and held him. “We’ll take you to her,” Andrew said.

Mark stopped trying to yank away, and a new coldness seemed to enter him. Wordlessly they walked through the building, out the far end, and along the pathways cleared in the snow to one of the dormitories. Now he struggled again, but briefly, and he permitted them to lead him to one of the rooms. At the door they all stopped, and then Andrew gave Mark a slight push and he entered alone.

“No!” he cried. “No!”

There was a tangle of naked bodies, doing all the things to one another she had told him about. At his scream of anguish she raised her head, as they all did, but he knew it was Rose his eyes had picked out of all the rest. She was on her knees, one of the brothers behind her; she had been nuzzling one of her sisters.

He could see their mouths moving, knew they were talking, yelling. He turned and ran. Andrew got in front of him, his mouth opening, closing, opening. Mark doubled his fist and hit blindly, first Andrew, then the other doctor.

“Where is he?” Barry demanded. “Where did he go this time of night?”

“I don’t know,” Andrew said sulkily. His mouth was swollen and it hurt.

“You shouldn’t have done that to him! Of course he went wild with his first taste of sex. What did you think would happen to him? He’s never had it with anyone at all! Why did that foolish girl come to you?”

“She didn’t know what to do. She was afraid to tell him no. She tried to explain everything to him, but he wouldn’t listen. He ordered her back night after night.”

“Why didn’t you come to us about it?” Barry asked bitterly. “What made you think shock treatment like that would take care of the problem?”

“I knew you’d say leave him alone. You say that about everything he does. Leave him alone, it’ll take care of itself. I didn’t think it would.”

Barry went to the window and looked out at the black, cold night. The snow was several feet deep, and the temperature dropped to near zero almost every night.

“He’ll come back when he gets cold enough,” Andrew said. “He’ll come back furious with all of us, and with me in particular. But he will come back. We’re all he has.” He left abruptly.

“He’s right,” Bruce said. He sounded tired. Barry looked quickly at his brother, then at the others, who had remained silent while Andrew reported. They were as worried about the boy as he was, and as tired as he was of the apparently endless stream of troubles caused by him.

“He can’t go to the old house,” Bruce said after a moment. “He knows he’d freeze there. The chimney’s plugged, he can’t have a fire. That leaves the woods. Even he can’t survive in the woods at night in this weather.”

Andrew had sent a dozen of the younger brothers to search all the buildings, even the breeders’ quarters, and another group had gone to the old house to look. There was no sign, of Mark. Toward dawn the snow started again.

Mark had found the cave by accident. Picking berries on the cliff over the farmhouse one day, he had felt a cold draft of air on his bare legs and had found the source. A hole in the hill, a place where two limestone rocks came together unevenly. There were caves throughout the hills. He had found several others before this one, and there was the cave where the laboratories were.

He had dug carefully behind one of the limestone slabs, and gradually had opened the mouth of the cave enough to get through it. There was a narrow passage; then a room, another passage, another larger room. Over the years since finding it he had taken in wood to burn, clothes, blankets, food.

That night he huddled in the second room and stared dry-eyed into the fire he had made, certain no one would ever find him. He hated them all, Andrew and his brothers most of all. As soon as the snow melted, he would run away, forever. He would go south. He would make a longer canoe, a seventeen-foot one this time, and steal enough supplies to last him and he would keep going until he reached the Gulf of Mexico. Let them train the boys and girls themselves, let them find the warehouses, find the dangerous radioactive places if they could. First he would burn down everything in the valley. And then he would go.

He stared at the flames until his eyes felt afire. There were no voices in the cave, only the fire crackling and popping. The firelight flickered over the stalagmites and stalactites, making them appear red and gold. The smoke was carried away from his face and the air was good; it even felt warm after the cold night air. He thought about the time he and Molly had hidden on the hillside near the cave entrance while Barry and his brothers searched for them. At the thought of Barry, his mouth tightened. Barry, Andrew, Warren, Michael, Ethan . . . All doctors, all the same. How he hated them!

He rolled in his blanket and when he closed his eyes, he saw Molly again, smiling gently at him, playing checkers, digging mud for him to model. And suddenly the tears came.

He never had explored the cave past the second room, but in the days that followed, he began a systematic exploration. There were several small openings off the room, and one by one he investigated them, until he was brought up by a sealed passage, or a drop-off, or a ceiling so high he couldn’t get to any of the holes there might be up there. He used torches, and his steps were sometimes reckless, but he didn’t care if he fell or not, if he got trapped or not. He lost track of how many days he had been in the cave; when he was hungry he ate, when he was thirsty he went to the entrance, scooped up snow, and took it back with him to melt. When he was sleepy he slept.

On one of his last exploratory trips he heard water running, and he stopped abruptly. He had traveled far, he knew. Over a mile. Maybe two miles. He tried to remember how long his torch had been when he started. Almost full length, and now it was less than a third of that. Another torch hung on his belt, just in case he needed it, but he never had gone so far that he had needed a second torch to get back.

He had lighted the second torch before he came upon the cave river. Now he felt a new excitement as he realized this had to be the same water that ran through the laboratory cave. It was one system, then, and even if no opening existed other than the one cut by the river, the two sections were linked.

He followed the river until it vanished into a hole in the cave wall; he would have to swim to go any further. He squatted and stared at the hole. The river appeared in the laboratory cave from just such a hole.