"You're the Green Tara," Shan ventured, "the one they bring water to."

"Not my idea, that name. It's embarrassing," Larkin said.

"A protector deity," Winslow said with another grin. He seemed unable to stop smiling. He had come to Tibet for a body and discovered a living woman.

Shan saw that one short line on the map, labeled seven, ran only for an inch on the paper, on the mountain above them, then continued for two inches in red dashes. "You plot river courses," he said in confusion. He spotted several long plastic tubes of colored powder leaning against the back wall. "You drop markers in rivers. But the rivers are already mapped. Why?"

"Not all are mapped," the American woman said. "Not this one. Not the Yapchi River."

"The Yapchi?"

"That's what we call it."

"What's a river in the mountains have to do with oil?"

Larkin sighed. "Do you know how many geologic mysteries remain on the planet? I mean major unknowns. A hundred and fifty years ago the sources of many major rivers had yet to be found. The tectonic plates had not been defined, or even theorized. Many of the world's greatest peaks had yet to be discovered. Vast regions had yet to be mapped. Today, outside the bottom of the oceans, what's left? In all my career I had never hoped to have a taste of such excitement. But then I came to Yapchi camp." Her gaze drifted toward Somo and the other purbas, still speaking in quiet tones. "After four days on this mountain I knew something was wrong. The water coming off the mountain wasn't nearly enough, given the size of the snowpack and dimensions of the watershed."

"You mean you discovered this river? But it's not a river. I mean-"

"It is and it isn't. It's a hidden river. A buried river. The river tumbles down the mountain for three miles and slams into this gorge. It's the wrong place, I thought at first. A fluke of the terrain, maybe just a temporary feature that happened this year because of a rockslide somewhere above that blocked the normal watercourse. Nature doesn't send rivers into deadend canyons."

"You mean it goes inside, underground from here," Shan said. "A new feature for maps of the region."

"Like the Upper Tsangpo." Winslow gave a low whistle. "You'll be famous," he said with a new tone of respect.

Larkin acknowledged Winslow's words with a surprised expression, a nod of respect. A few years earlier a team of American explorers had gained international notoriety by scaling a treacherous, uncharted gorge in Tibet to confirm the existence of a beautiful waterfall that had been spoken of in Tibetan myth.

"But why would Zhu hate you for that."

Larkin looked at the man with Somo then at the two older men at the table, who continued to work at the microscopes, pausing sometimes to lift water from the test tubes with small droppers. "He doesn't like my helpers."

Shan stared at the two Tibetans. They were not purbas, or at least not like any he had known. They looked like professors. Somo appeared at his side. "They are friends," she said pointedly, meaning that no one would offer their names. "Beijing will be furious," Larkin said, her eyes suddenly flush with excitement. "The discovery will be announced overseas, and credited to Tibetans. And if we discovered that it emerged north of the mountains it would be the new headwaters."

The Tibetans all grinned at Shan. Larkin meant that the little river they had discovered would be the new source of the Yangtze, China's greatest river, announced and proven by Tibetans. Beijing would indeed be furious. Beijing would be apoplectic. It was Shan's turn to grin.

An hour after dawn the next day they arrived at the high, remote clearing where Shan, Winslow, and Somo had been dropped by the helicopter the day before. Long rays of sunlight cut horizontally across the windblown ridge. The supplies had not arrived. The two purbas who had been with the map the day before stole away in opposite directions to circle the landing zone. Larkin had not accepted that Zhu wanted to do her harm, but she had agreed to leave early for the supply drop, and had listened with an amused expression to Winslow's suggestion that they might want to test Zhu with a trick. If Zhu were indeed intending to harm Larkin, he would not come in the helicopter with the supplies for fear of frightening her away, and because the pilot might become a witness. He would have himself dropped perhaps a mile away and wait until the helicopter completed the supply drop. The purbas would watch the trail that led to the nearest clearing, the likely dropoff point, while Winslow rigged a decoy. "Be careful. Watch everywhere," Somo warned the two sentries as they began to jog to their post. "We don't know where that hidden patrol is." Hidden patrol. The words caused Shan to survey the rugged landscape again. She meant Tuan's hidden squad of knobs.

Larkin still gazed with amusement as they watched from the rocks. She had seemed touched that Winslow had gone to such lengths to locate her, but although she did not give voice to the point, it seemed apparent she thought she needed no one's help. Yet the two Americans had warmed to each other, preparing the evening meal together the night before, and walking side by side on the trail that morning, sharing stories of home and mindless bureaucrats and experiences in Tibet, laughing softly together sometimes, even pausing to watch a hawk floating in the mountain updrafts.

After an hour of watching from the rocks Larkin gave a conspicuous yawn, casting an impatient glance at Winslow, then produced her spiral pad and began studying her notes.

Somo seemed troubled somehow. Finally she cast an anxious look toward the rocks on the opposite side where the two purbas kept watch, then turned to Shan. "They didn't want me to tell. They don't know you, said you and I were not part of this project. But you have to know. It's just that those bottles of water that go to the Green Tara. Sometimes they come with messages."

"Secrets," Larkin interjected, with a tone of warning.

"Sometimes about movements of knobs and soldiers, and Religious Affairs. Lokesh and Tenzin are not at Yapchi. But for the past two days none of them have moved south into Amdo town or north into Wenquan," Somo reported. "And no helicopters are known to have landed at Yapchi or anywhere else within twenty miles."

Winslow opened his map with a puzzled look, and shared it with Shan. Wenquan was the first town in Qinghai, going north. Amdo was the next town south for anyone going toward Lhasa.

"They weren't taken where anyone would expect," Somo said in a hushed, urgent voice. "Not to jails. Not to Lhasa. Not to the airport to be sent to some other prisoner facility. Not to any known reprogramming facility." There was nothing on the section of highway between the cities, except a short thin grey line intersecting it from the west. "There is only one place," she said, pointing to the end of the line. "Norbu gompa."

It made no sense. But it would make less sense for Religious Affairs and the soldiers to hold the prisoners at Yapchi, and certainly the soldiers knew about Norbu. Shan's mouth went dry as he recalled the political signs at the gompa, the strange, bullying air of the men in white shirts and the predatory gaze of Chairman Khodrak.

"And there's something else, something that has the others confused. The howlers and the soldiers had a big argument at Yapchi. Tuan and one of Lin's officers were shouting at each other the night after Tenzin and Lokesh were taken, and the next morning Tuan and all his men were gone."