"Go!" the American shouted again.

Shan shot forward ten feet and turned just as the entire roof around the weakened support collapsed. Deacon was halfway through as the stone and sand closed over him. Shan reached out and grabbed his flashlight with one hand, then grabbed Deacon's wrist with the other and pulled.

With a great heave the American came out of the rubble. He lay face down, gasping for a moment, then took the light and shined it forward, into the face of each of those ahead of him. "Okay," he said with a forced grin. "Guess Bao can't hear us now."

"Where exactly is the exit you promised?" Jakli asked slowly, each word sounding like a vast effort of self-control. The light barely reached her face. Beyond her was the vague shape of the tunnel extending a few feet, then blackness.

"There's access, has to be. There was a community here. You saw the stone ruins," Deacon said. "And cisterns. Almost all the cisterns have been sealed off at the top, but they might have only a foot or two of desert above them."

"But when?" Kaju said, unable to hide the fear in his voice. "Where is a cistern? It's hard to breathe."

"I think Mr. Deacon is saying we just keep going," Shan offered.

"Right," Deacon said in a subdued voice. "A few more days, maybe we'll come out in the northern mountains, with frogs in our pockets." He aimed his light at the boys' faces. "They say there's treasure in some of the old Karez," he offered with hollow enthusiasm.

Batu smiled. Jengzi looked at the American with skepticism, but they both began to crawl with new energy, following Jakli as she probed the darkness.

No one spoke for several minutes, as though fearful that a sound might shatter another of the frail supports. Then Kaju suddenly stopped. "Here!" he said, and pointed to the beam above his head. "We have protection."

As Deacon raised the light, an inscription painted with crimson pigment in Tibetan script could be seen. "The six-syllable mantra," Kaju said with a glimmer of hope in his voice. "The tunnel has been blessed."

"Again!" Jakli called out, pointing to a beam near her own head. The same inscription, in the same paint. She crawled ahead at a faster pace, as though the mark might portend a portal. As Shan watched, she faded into the darkness, but the sound of her movements continued. Then suddenly there was a sound of stones falling and a splash. Jengzi called out Jakli's name in alarm. There was no reply.

"Nobody move!" Deacon warned. "Not a muscle. Not a hair. I'll go."

"No," Shan said. "You're in the back. Pass the light to Batu."

The boy's eyes were wide with fear, but he took the light without speaking and inched forward. He moved twenty, then thirty feet in front of them. Jakli's voice could be heard in the distance, echoing as though in a hollow chamber. The muffled words of a conversation rolled down the tunnel and then, incredibly, laughter. Kaju and Jengzi shot forward, followed closely by Shan and Deacon.

Shan and the American arrived to find Kaju and the boys arrayed on a stone ledge, depressed along its bottom to continue the main course of the karez as it curved around a huge hole lined with stones. The cistern that had been designed to capture the overflow from the main channel was at least forty feet in diameter under a dome of tightly fitting cut stones, and had been built in four tiers, each several feet higher than the one below. Jakli stood below them, on the top tier, up to her waist in water, her head three feet below the top ledge.

Deacon whistled in awe at the construction as he shined his light along the ceiling and far wall. Roots pierced the stone at the apex of the chamber. Shan remembered the surprisingly vigorous clump of shrubs that grew near the far end of the bowl.

"With Jakli's permission," the American said, "I will record Batu and Jengzi as the discoverers. The solvers of the great mystery."

"Mystery?" asked Kaju.

"Sure. We just found out why this place has always been called Stone Lake."

The boys wore grins that nearly reached their ears. Jakli splashed them from below.

"If there was a cistern," Shan suggested, "there must have been access."

Deacon was already easing himself along the ledge toward the far wall. "Probably a stone stairway leading down from something like a bath house." He stopped and aimed his light at a point just below where the dome began on the opposite side. "Right about there," he said. A large stone could be seen, supported by two cut-stone posts. But the area below the lintel stone was packed with rock, sand, and timber debris. The entrance had collapsed.

As Shan and Kaju reached down and pulled Jakli onto the ledge, Deacon's light searched the side of the cistern. "It's too fragile here," the American concluded. "We could collapse the whole thing by moving the rocks. But the cistern would have been near the center of the settlement here. There will be more access ahead."

Just as his hopeful words rang out his light flickered and went dim. He shook it and it brightened, though not nearly to the brilliance it had a moment before. "Go!" he barked.

Two hundred feet past the cistern, Jakli, in the lead, asked for the light. A moment later she began describing in a shaking voice what lay ahead. But there was no need for words. The beam of the light told them everything. Several side posts were loose, three of them fallen and leaning across the tunnel. One top beam had fallen to the bottom and had a pile of sand and stones around it. Another small beam was rotted away, with little more than a few splinters holding it up. The tunnel appeared ready to collapse at any instant.

Time seemed to have a different quality in the tomblike stillness. The small party stared at the doom ahead, and Shan had no idea how long it was before Deacon spoke.

"Okay," the American said in a taut voice. Shan heard him breathe deeply, as if trying to calm himself. "It'll be like this. The light stays with Jakli. She goes first, then the boys. We need someone strong behind, in case there's quick digging to do, so Kaju goes, then Shan. Call back when you reach a stable zone, and I'll come. I'm the biggest, and so the most dangerous."

No one argued. Jakli began inching forward.

"You'll have no light," Kaju called back to the American.

"I got matches," Deacon said in a hollow tone. "No problem."

Shan urged the Tibetan forward with a touch on his leg, and gradually the four in front made progress. Ten feet, proceeding with agonizing slowness, then twenty feet, and the light began to quickly fade, as if perhaps the tunnel had curved.

"I know you're here, damn you," Deacon said in the darkness. "You're smaller than Kaju. You can make it."

"I thought there might be crickets," Shan said. "Why should you have all the fun?"

There was silence for a long time. When he listened hard, Shan thought he could hear particles of sand turning over.

"How many do you have?" Shan asked. "Matches."

"I just counted. Ten."

"I've got maybe half a dozen." Shan said.

"Great. Run out for marshmallows. We'll have a roast."

"Marshmallows?"

"Never mind."

Silence again.

"I got Old Ironlegs to sing," Deacon announced through the darkness. "Big bass voice. I fed him some peanut butter."

They spoke of crickets again, of the ones the old monk had when Shan was a boy and those Deacon had collected so far for his son.