A beam sagged as Deacon passed, then broke behind him. They crawled like snakes over a pile of rubble that rose to half the height of the tunnel. Shan moved at a snail's pace, knowing that his next movement could be his last. Their progress was agonizingly slow. The wall shifted once, and buried Deacon's arm. Slowly the American dug himself out, then gestured Shan on. Twice the torch dimmed, as if about to extinguish, but Shan thrust it forward as far as he could reach until it found oxygen and revived.

Suddenly Deacon called out in a loud whisper, "The wall!"

On either side was solid stone, huge cut pieces, with long slabs of stone overhead.

"A building foundation!" Deacon croaked excitedly. "It would have access, a tap to the karez."

They moved faster. Then, twenty feet later, Shan froze. A spirit hovered fifteen feet ahead of him, a shape that glowed and shimmered. Deacon saw it and cursed. Shan crawled closer and his heart leapt. It was light, a small shaft of sunlight. But it came through a tiny crack in the stone, only a quarter-inch wide.

The tunnel curved as they proceeded, then suddenly Shan saw a fire with a face in it, a sight that frightened him so much he dropped the torch.

Then the face spoke, with a woman's voice. "Shan!" it called, and they saw it was Jakli, with a torch held below her face.

In five minutes they were out, gasping great lungfuls of fresh air as Akzu and Kaju pulled them through a two-foot opening in the tunnel ceiling, into painful, brilliant sunlight. They were at a ruin in the side of the dune at the northern end of the bowl.

"The flashlight was almost out," Kaju explained, extending a water bottle. "We couldn't use it to go back. Then it took so long to find wood for a torch."

They drank in great gulps as Jakli and the boys explained to Akzu their ordeal in the darkness and the miraculous appearance of Deacon and Shan.

But Shan wasn't celebrating. He was exploring for papers he hadn't burned, the ones that he hadn't reached in the tunnel. The small folded paper of abbreviations from the dead American was still there. He refolded it and stuffed it into his shirt pocket. The only other paper was the map he had drawn of Karachuk. He turned the map over. It had been in the trash, used by the Tadjik to wrap the baseball he had stolen. It had been nothing, he had thought then, just blottings from a pen, strange lines in different degrees of shading.

Deacon approached him and handed him the bottle. "I was thinking, Shan," he said, squatting by his side. "You should come. Next week. Under the moon, with my son and me. I want you to. I was gone down there. You saved my life."

But Shan only half listened. He was watching Jakli, who now stared at him with anguish in her eyes. She stepped away from Akzu and approached him. "Bao didn't leave because of what Akzu told him," she said. "He left because there was a report on his radio that two old Tibetans had been seen on the highway."

Shan felt his head sag. He stared absently at the paper in his hands, fighting a wave of despair, until suddenly the American grabbed the top of the paper and pulled it toward him.

"Where the hell-" Deacon exclaimed and bent to examine the line of tiny print at the top of the page.

"That Tadjik had it," Shan said, "the one at Karachuk. Do you know what it is?"

"Of course. Genetic mapping sequences. A copy of our lab results. What's the point?"

Shan thought a moment and looked up with alarm in his eyes. "That Tadjik was much smarter than I thought. He wasn't trying to steal your white ball. The ball was cover, a distraction in case he was caught. He was trying to steal this, to take it to someone."

"Jesus." Deacon sat down heavily on the sand and pointed to the print at the top of the paper. "A lab registration number, for our lab in the United States. Big secret, until we publish. This lab code gets out, everything gets shut down. The knobs will know who we are. Washington and Beijing will be all over us." Deacon gulped down the remainder of the water and tightened the straps on his backpack.

Shan had one match left. He used it to burn the paper, then watched the American with a pang of guilt as he jogged off to his horse. He hadn't told the American the worst of the news, that his son, the last of the hidden zheli, was now undoubtedly the next target of the killers.

Perhaps, he thought absently, there would have been advantages to being buried in the desert. Now, finally, he had to decide. Others were going to be taken, to be killed or imprisoned. He couldn't stop it all. He could try to save Gendun and Lokesh or he could try to stop the zheli killing. But he couldn't do both.

It seemed like days had passed inside the karez, but it was only early afternoon by the time they reached the highway. Akzu embraced Jakli repeatedly as they departed, making her promise with each hug to be at the nadam early, until she began to smile, then softly laugh. Her aunts had secretly made a wedding dress, he told her, so she had to come early but act surprised. Before the Kazakh left, Shan asked Jakli if she knew the way to the camp where Marco had sent the Tadjik thief. She consulted her uncle briefly. Wild Bear Mountain, Marco had said, near the ford of Fragile Water Creek. They did not know the camp but they knew where to find a guide who would know.

"I thought a dust demon had taken you," Akzu said in a distant voice before departing. "They do that sometimes." He had listened in seeming disbelief when they had explained their passage through the tunnels, and now looked at the sand on their clothes, their skin, their hair and nodded solemnly, as though confirming his suspicion. "Sometimes, they bring you back just as sudden," the old Kazakh observed. "You wouldn't remember," he added solemnly.

Kaju studied the landscape with an unsettled expression, as if looking for other escape routes. He would have to come back in five days, for the next class. He had promised the American, for that was the appointed time for Deacon's son to return to his parents.

Jakli seemed to sense Shan's thoughts as they drove west, away from the desert. "He's out there, with Sophie," she reassured him. "Marco will find your friends. There is no one better for the task. He will take them to safety. They're probably on the way to his cabin now, singing Russian love songs with him."

Half an hour later Jakli eased to a stop at a crossroads jammed with people. Near the intersection was a shack with a wire fence behind it, holding a flock of goats. They stopped and walked to the gathering. More than two dozen people crowded the intersection, some carrying stones, others sitting in reverence before a growing cairn of rocks. Some were listening to a man who sat atop a broad log that served as a corner fencepost, speaking with great animation. A man on a horse rode up and asked where the holy place was. The man on the post pointed to the rocks and the other man dismounted, untied the wing of a large bird from behind his saddle, and walked to the rocks to fasten it to the cairn.

It was a shrine. For the miracle that had happened. The people were kneeling now. The rocks were arranged in a narrow pyramid nearly eight feet high. A rope was tied to a stick at the top, staked to the ground fifteen feet away, and a fragment of cloth was attached to it with Tibetan words. A prayer flag. Shan watched in confusion. Buddhists, down from the mountains, were putting on prayer flags. The Kazakhs and Uighurs were putting on feathers, pieces of fur, and the wing of a bird.