"You all right?"

"What do you think?" Lin Yao didn't say anything else, just found another crevice in the rock and then another, her toes scrabbling to keep their hold. And as she finally pulled herself clear of the icy water, Chuang Tzu reached for the handhold she'd used to begin her climb and pulled himself close to the rock-face.

"Keep going," he said. "Don't look down."

He was staring up at her, Lin Yao's whole body foreshortened into legs, buttocks and a narrow, almost hairless gash of sex.

Everything was a matter of perspective, Chuang Tzu realized. Ordinary things seen from extraordinary angles held their own meanings and messages. What her buttocks and sex said to him the boy was still working out when the girl scrambled over the lip of the pool and his perspective changed.

"Well, that was stupid," said Lin Yao.

Chuang Tzu shrugged. "Quite probably."

"That's all you can say?"

It was the climb, decided the boy. She must have known he was staring or else realized that not doing so was next to impossible.

"Here," said Chuang Tzu, picking up his shirt. He wrapped the garment around Lin Yao and then put his old jacket on top. "You need to get warm." They sat in silence after that. Which was to say that not a word passed between them, although icy water continued to roll over the lip of the fall and crash into the pool below while buzzards circled high in the sky overhead, their cry harsh and unlovely.

Down in the valley a boy shouted and army trucks ground their gears as they began to climb towards the pass. In short, the world continued around them as they sat, side by side, on rough grass in the weak sunlight of a late afternoon.

"I'm sorry," Lin Yao said finally.

Chuang Tzu glanced across. "For what?"

"Being cross."

It was the first time she'd ever apologized to him and the very fact she had gave Chuang Tzu a tiny, flawed advantage. "You weren't cross," he said, "you were furious."

When Lin Yao blushed, Chuang Tzu reached across and took her chin gently in his first finger and thumb, turning her head until she faced him. Their kiss was slow and tentative, her lips softening just as he was about to bring the kiss to an end.

"Love you," he said, the only time he'd said that to anyone. With Wu and Wu's sister it would have seemed clumsy and provincial and there had been no one else to whom he could say those words.

Grandfather Luo would have laughed at him and talked of selfish genes and bonds of affinity, while Madame Mimi would have grown tight-lipped and angry. Any talk of emotion within the family had that effect on her.

"What are you thinking?"

"About stuff," the boy said.

"What stuff?"

"Families. Children. Stuff like that."

Lin Yao's eyes went wide and for a second she looked shocked. Then she looked puzzled as if she might have misunderstood what he said. Which she had, but Chuang Tzu only realized that later and by then the SZ Loyal Prince was beyond the moon and he was accelerating out of her life.

Lin Yao let the boy lower her onto the rough grass and gently spread her knees. They began with Dragon Turns, in which the man lies between the legs of the woman. Missionary, Grandfather Luo called it. Suitable only for nervous young women and foreigners.

Chuang Tzu sucked the fingers of his right hand and carefully cupped her entire vulva, smoothing one finger between dry lips. Then he did it again, pushing the finger slightly inside her.

Sore from their previous attempt, Lin Yao tensed at his touch.

"I'll take it slowly..."

The boy waited for her to say no but she just looked at him. A third helping of saliva and Chuang Tzu knelt himself between the girl's legs. In the end it took two of them, Lin Yao spreading herself with her fingers while the boy used his own hand to position himself against her.

"Slowly," she warned.

So Chuang Tzu pushed forward, very slowly, feeling the tiniest jolt as Lin Yao's body opened just enough to let him almost enter and then tightened around him. Not knowing whether to push deeper or pull back and try that bit again, Chuang Tzu waited. With Wu's sister it had been easy. She just performed Jade Girl Plays the Flute and then jumped on top of him, there was nothing fragile about it.

In the end, Lin Yao solved the problem for him, pushing up with her hips. One wince and the thing was done.

They stayed so for a while, Lin Yao still wrapped in his shirt and coat and the boy naked above her with a cold, almost autumnal wind blowing across his bare back.

Eyes open and watching, they kissed and kept kissing until their eyes closed and the world disappeared. Lin Yao was grinding against him now, her teeth biting at his lower lip. So the boy bit back, hard and then more softly, feeling her body tense and her arms lock suddenly across his back.

A yelp like a wildcat released her. Lin Yao's head falling back, pillowed on her blouse and the rough grass. When her breath had returned and small tremors stopped running the length of her abdomen, the boy pulled back and then slid slowly in again, feeling an answering ache begin to build in his own body.

He should pull out, Chuang Tzu knew that. Spurt his hunger onto her thin belly or roll the girl over and release himself against the groove of her buttocks, but instead he gripped Lin Yao's arms and lost everything in the moment.

"You okay with that?"

Lin Yao nodded. She was sitting on her heels, Chuang Tzu's shirt still wrapped tight around her, a darkness between her legs where he'd so recently been. The boy could smell himself on her, the scent of sex rising like steam from her body, richer than musk and dark as gun-powder tea.

"We should get back," he said.

"Why?"

"Because my grandmother will be worried."

"And you worry when your grandmother is worried?"

"Of course." Chuang Tzu looked at her. "Don't you?"

"I don't live with my grandmother," said Lin Yao. And Chuang Tzu suddenly realized he knew almost nothing about who made up Lin Yao's own small household.

"Well, your mother," he said.

"My mother's dead." Lin Yao's voice was slightly surprised, as if she'd expected him to know this and perhaps he had.

"I'm sorry," he said finally.

"It was years ago," said Lin Yao, and Chuang nodded, although that hadn't been what he meant. And so they sat in silence for a few more minutes, while the sun snagged on a distant mountain like a lost balloon and the water in the pool changed from gun-metal silver to black.

"I need to go," Chuang Tzu said. "First I'll walk you home."

"Walk me home..." Lin Yao glanced at him, eyes wide. A thousand colours reduced to rust. "Am I going to see you tomorrow?"

"Of course... I promise."

"I don't believe you." Tears rolled down Lin Yao's beautiful cheeks and hid themselves beneath the neck of Chuang Tzu's jacket as she dressed in silence, with her back turned to him.

"Tomorrow," promised Chuang Tzu, when they reached the gate of her tiny farm.

Lin Yao shook her head.

It was late when the boy got home and later still when his grandmother gave him the letter which had arrived that afternoon from Wu. Only now, instead of a lieutenant, Wu was a major commissar and the youngest member of a panel headed by General Wu, his father.

Chuang Tzu's one-time friend wrote to say that great opportunities awaited those who joined the newly built SZ Loyal Prince and both Wu and his sister had taken the liberty of mentioning their friend's talents to the General, who was delighted with the suggestion.

Enclosed with the letter came a travel permit, a ticket for a government flight from Leshan to Wuhai and a letter, signed by General Wu himself, congratulating the young man on being chosen for the most important project undertaken since Qin Shi Huangdi ordered that slaves join together some small and rather useless defences to make the Great Wall.