"Peridot and lapis lazuli," Costas exclaimed. "That combination again. Who was his ayah?"

"His nanny," Jack murmured. "She looked after him when he was a boy in Bihar, where his father had an indigo plantation near the border with Nepal. She was the great-aunt of Howard's servant Huang-li, the one who waved them off from Quetta in 1908. During the Indian Mutiny, when Howard was a little boy, she took him up into the Himalayas. Later she became his own children's ayah, and then the next generation's. n.o.body ever knew how old she was, but she lived to be well over a hundred. In the 1930s, she retired and disappeared to live out her remaining life in the mountains of Tibet. She was never heard from again. She claimed that her ancestors came from far away in the east, from northern China. When my grandfather was a boy she told him stories of the First Emperor, the great emperor Qin who unified China in the third century BC. She told him she was descended from the guardian of the First Emperor's tomb. A legend, perhaps, but it enthralled my grandfather. One of the other books he gave me was the Records of the Grand Historian, the account of the dynasty of Qin. It had been another one of John Howard's books, found in his study after he disappeared."

"Speaking of family legends, what about Howard's disappearance?" Costas said. "Talk about something that would have enthralled children. You must have wondered whether he and Wauchope found some fabled treasure and lived out their lives like kings in some hidden mountain fastness, just like Kipling's story."

"Well, there was one story. It was told by Howard's wife, my great-great-grandmother. Everyone except my grandfather dismissed what she said because she'd become unwell. Howard had done everything he could for her. But as soon as their children had grown up, she deteriorated. She'd never been able to deal with the death of her first son. She was looked after by her sisters, but then she went into an inst.i.tution. Howard had money from his father's indigo fortune, and no expense was spared for her comfort. Only when he knew there was no hope did Howard return to India. But he saw her again in England several times before he disappeared, the last time in 1907 just after he retired. He took her away for a few days to a cottage on the Welsh border. It seemed to be a brief window of happiness. It was a beautiful early summer, and they walked in the hills. That was how she remembered it, in a moment of lucidity when my grandfather visited her in the hospital years later. After Howard met up with Wauchope in Quetta, he never saw his wife again. But she lived for many years longer, in a kind of shadowland, not dying until 1933."

"Did she remember anything else?" Rebecca said, her voice emotional.

"She told my grandfather that when she shut her eyes tight, she was standing, holding hands with her son Edward, looking into a place of sparkling beauty, like a magical cave. Only Edward was older than he ever was, a little boy, not a babe in arms. Then she saw Howard, a proud young man in uniform, a twinkle in his eye, little Edward's father, her beloved husband, and the little boy ran, arms outstretched, crying out the word Dada over and over again, a word he had barely been old enough to say in his short life. She said in that moment she was in the perfect place. She spent a lot of time in that hospital with her eyes shut tight."

Rebecca was in tears, and Jack held her hand. "She did say one other thing. Everyone dismissed it because the hospital was run by nuns, and they thought she was just repeating some religious mantra. She said her husband had gone in search of the Son of Heaven."

"A Christian nunnery?" Costas said. "They must have said that to a lot of widows."

"That's what everyone thought." Jack leaned forward, his eyes ablaze. "But for my grandfather, then a young naval officer, it struck a chord and stayed with him. Fifty years later, when he was an old man himself, he called me at school. He was incredibly excited, and I had to drop everything and visit him. That was when he gave me the Records of the Grand Historian. He'd been thumbing through it, and he saw those exact words. Son of Heaven. He suddenly remembered where he'd seen them before. As a naval cadet, he'd put in at Shanghai and traveled to Xian, to see the fabled tomb of the First Emperor. His photograph of it in 1924 was one of the earliest to reach the west. That was where he'd seen those words, Son of Heaven. It was the traditional t.i.tle of the Chinese emperor."

Rebecca wiped her eyes. "I remember it. The terracotta warriors exhibit."

"But there's more to it than that," Jack continued. "My grandfather had dug out his old print of the vast tomb mound, as big as an Egyptian pyramid, still completely unexcavated, years before the terracotta warriors were discovered. The tomb of the First Emperor, of Shihuangdi, Son of Heaven. He had the Records with him, and read the pa.s.sage describing what was inside. Fabulous treasures, a replica of the world in miniature, the chamber decorated to represent the heavens, with the greatest light of all falling on the tomb. Then he had a brainstorm. That was when he called me. Howard's wife wasn't saying Son of Heaven, but Sun of Heaven. The sun, the greatest light in the sky, the light that would ensure the emperor's immortality. The greatest jewel in the heavens. That's what Howard's wife had meant. He had told her he was going in search of a fabled lost jewel."

"I knew it." Costas grinned. "A treasure hunt."

"All that stuff," Rebecca murmured. "How you thought it out, Dad. Pretty cool."

Jack sat back. "All I've done is open up an old chest of drawers and let it spill out."

The red warning light flashed above them. Jack glanced at Rebecca's seat belt and then out of the window, into the gray light of dawn. The descent to Bishkek airport was b.u.mpy, through fierce crosswinds. Through holes in the cloud he saw flashes of land below, a dull flat wasteland and the airfield perimeter. A line of giant C-7 Galaxy transport aircraft stood on the tarmac, where the U.S. transit base for Afghanistan shared the runway with the civilian airport. The engines of the Embraer suddenly revved up to a whine. They had been b.u.mped down too low, and were doing a circuit before landing. Jack sat back and shut his eyes, feeling tired enough to fall asleep in an instant. He suddenly had a vivid picture of his grandfather's face, from the day they had spent together poring over the Chinese records. His grandfather had told him about the age-old quest for eternal life, about the First Emperor's expeditions to find the sacred Isles of the Immortals. Jack had only been a boy, but he had told his grandfather how one day he would search for treasures like that. He remembered what his grandfather had told him as they parted, the last time he ever saw him. He said he had sailed over a million miles in his life at sea, and that it was the journeys he relished most, not the destinations. Now, years later, after half a lifetime spent hunting down the greatest treasures in the world, Jack thought he understood. And then he remembered his grandfather playfully jostling him, and pretending to be an old Chinese sage. Beware the Sacred Isles. The quest for immortality is a fool's errand, and the First Emperor was the biggest fool of them all Stray too close, and you face mortal danger The plane jolted violently. Jack opened his eyes with a start. Costas was staring across at him, in some kind of droll amus.e.m.e.nt. Jack guessed what he was thinking.

"Looking forward to seeing Katya?" Costas asked.

"Looking forward to seeing what she's found," Jack replied.

"Dad." Rebecca gave him a scornful look.

"Okay, okay. Looking forward to seeing her," Jack said. "But she's stuck out there by the lake because I suggested it. I'm visiting her in a professional capacity. I have a vested interest in this project."

"When you meet her, Rebecca, just don't use the word girlfriend," Costas muttered. "If you don't want to bring out the Genghis Khan in her."

"Give me a break," Rebecca said. "What's going on here? Sounds like you guys need a reality check. Katya and I are both women. We can talk."

"Fortunately," Jack said, smiling sweetly at her, "you're not going anywhere near Katya today. After finding those bodies in the jungle, I'm not taking any chances. Katya was close to her uncle and involved with his research. If he was on a hit list, then Katya might be too. And that puts anyone around her in potential danger."

"Have you told her about him?" Costas said.

Jack held up his cell phone. "Just before we took off And she had some news to tell me too."

"So you're saying I can't come," Rebecca said defiantly.

"You're going to stay with Ben and Andy at the base, and help them with the equipment. Then you're going to fly east with them in a U.S. Air Force Chinook to the far end of Lake Issyk-Kul. That's where submerged ruins have been found. I promised we'd check that out too, as well as seeing what Katya's got for us. You're going to help set things up there, and wait for us."

"So I miss all the action," Rebecca said.

"You're going to be with a team of U.S. Navy SEALs," Costas said. "Can't get much better than that."

"You speak Russian, don't you, Rebecca?" Jack said.

She nodded, then looked at Costas. "The people my mother sent me to live with in New York are Russian. Petra and Michael defected in the mid-1980s, while they were in America at a conference. They're both palaeolinguists. Petra had been allowed by the Soviets to study in Italy, where she became my mother's best friend. That was before you two met, Dad, so you wouldn't have known her. After she returned to Moscow she met Michael at the Inst.i.tute of Palaeography."

"That's where Katya's based, isn't it?" Costas exclaimed.

Rebecca nodded. "I knew about Katya way before I first met you, Dad. The first time I ever saw you and Costas was when I was sitting down one evening at our summer cottage in the Hamptons with Petra and Michael, watching a doc.u.mentary about Atlantis. Katya was being interviewed."

"Small world," Costas said.

Jack looked out of the window, suddenly overwhelmed. He still had so much to learn about his daughter. It seemed inconceivable that he had only known her for a few months. He took a deep breath, and sat back. They were on the final approach now, and the plane was rocking about in the turbulence. He looked at Rebecca. "It's a serious job. Your Russian will come in very handy. The place you'll be going to on the lake is a Russian submersible warfare testing facility, recently reopened on the site of the old Soviet base. It's been a major coup getting them to agree to an IMU team operating in their restricted area, and for the U.S. military this is a lot more than just an interesting holiday for Special Forces out of Afghanistan. It'll require tact, poise and charm. It'll be your first official IMU role."

"But Costas hasn't taught me to dive yet," Rebecca said.

"Because Costas hasn't been allowed to take you to Hawaii yet," Costas grumbled.

"You can drive the boat," Jack said.

Rebecca perked up. "Where is it?"

Jack pointed down to the aircraft's floor. "Packed up in the hold. Brand-new Zodiac 6.5 meter rigid inflatable boat, twin 80 Evinrudes, state-of-the-art GPS navigation, position-fixing and bottom-profiling equipment."

"Cool."

Jack grinned at Costas. The plane's wheels skidded on the tarmac, and the nose settled down. The engines went into reverse and Rebecca shouted over the noise. "So when will I see you?"

"Don't know." Jack's voice was shuddering with the plane. "Depends on what Katya's found. Could be with you later today. But could be a little diversion."

"A little what?"

"A little diversion."

Costas looked despondently at his Hawaiian shirt, then at Rebecca. "By now, you should know what that means."

Jack and Costas stood beside the lake and waved at the army truck as it trundled off east, revving through the gears and disappearing over the ridge. After leaving Pradesh and Rebecca at the air base they had endured an exhausting four-hour journey from Bishkek, crammed into the cabin with the Kyrgyz driver and his guard. The U.S. Army Chinook helicopter which was meant to have brought them here had developed mechanical trouble, and rather than wait in Bishkek and risk losing a day they had opted to hitch a lift on a supply truck heading to the naval test base at the far end of the lake. Jack's antic.i.p.ation had risen over the last hour as the truck had lurched its way toward the lake, through an extraordinary landscape of ravines and ridges formed by the raging cataract that had once flowed from the lake, now shaped again by the wind. He had imagined the thoughts of travelers who had once braved the pa.s.s, knowing that each dark recess might conceal a robber band, ready to inflict the murderous fate that had befallen so many on the Silk Route. And then the truck had mounted the final rise and they had seen Lake Issyk-Kul stretched out before them, with the snowcapped peaks of the Tien Shan Mountains lining the far side. The driver had stopped abruptly and gestured across a rocky field toward a solitary yurt, a traditional Kyrgyz tent. They had thanked him and jumped out, and now they slung their rucksacks and began to pick their way across the rocky landscape. Jack began to see the features that had made this place so beguiling to Katya: swirling, curvilinear patterns on the boulders, carvings that looked as old as the rocks themselves. He stopped at one, putting the flat of his hand against it, feeling the hand of the sculptor more than two thousand years ago.

"A cemetery?" Costas said from behind. "They look like tombstones."

"Possibly," Jack said. "But there's lot of shamanistic stuff here too. It goes on for miles, where boulders have tumbled down the slopes and come to rest near the lakesh.o.r.e. Katya thinks the earliest petroglyphs date from the Bronze Age, from the late second millennium BC, but nomads were carving here right through the period of the ancient Silk Route, to the later first millennium AD. As well as the nomads, traders made their way east or west among these boulders for thousands of years; stopping here after surviving that pa.s.s or before risking it. In addition to all the nomad art, there's a chance of finding something really amazing, inscriptions made by those people - Bactrian, Sogdian, Persian, Chinese, you name it. Those traders are what give this route its place in history, yet they hardly left an imprint at all. Any discovery could be a huge revelation."

Jack shaded his eyes and looked across the field of boulders, away from the lake and back toward the pa.s.s. The late afternoon sun was in his eyes, and it was impossible to see much, flashes of light off the weatherworn surfaces of the rock, shadows where there were gullies and ravines. It would be very easy to get lost in this place, and very easy never to be found again.

"There they are," Costas said. "I can see Katya. Come on." Costas looked faintly out of place in his baggy shorts, oversized Hawaiian shirt, hiking boots and wraparound aviator sungla.s.ses, but he was surprisingly agile and leapt nimbly from rock to rock. He reached a tall man in a felt hat who stood up among the boulders and shook hands. Jack joined them and shook hands too. The man was about his own age, with blue eyes, his face etched by sun and wind in the way of steppeland people. Katya stood behind him, looking as if she also had taken on the hue of the landscape. She caught Jack's eye and flashed him a quick smile, but her expression gave little away. She turned to the man. "Meet Altamaty," she said. "He's curator of the Cholpon-Ata open-air petroglyph museum. As well as his native Kyrgyz, he speaks Russian and Pashtun, but he's only just started to learn English. He's got diving experience with the old Soviet navy. He wants to be involved in the underwater investigations at the eastern end of the lake. I spoke to you about him, Jack."

"Where's the museum?" Costas asked.

Katya gestured around. "You're standing in it. It's probably the largest museum in the world. And the most under-resourced. It's basically a one-man show."

Jack looked at Katya. She was wearing faded military-surplus trousers and a khaki T-shirt, her forearms caked with dirt. Her long black hair was tied back and her face was deeply tanned, accentuating her high cheekbones. She looked more tired and weatherworn than the last time he had seen her, at the conference three months ago, but the color suited her. Jack knew that her mother had come from this area, and her face seemed at one with the tall Kyrgyz man beside her.

"I've already briefed our people about Altamaty," Jack said. "As soon as the Chinook's airworthy, Ben and Andy are flying from Bishkek straight to the old Soviet naval base at the eastern end of the lake. The Americans have already got things up and running there, and I want divers in the water as soon as possible to show what we can do. Rebecca's going with them."

"Your daughter is with you?" Katya said.

Jack had told Katya about Rebecca for the first time at the conference. "I was going to bring her here, but not after what happened to your uncle in the jungle. This place might be over the danger threshold. And she'll have enough on her plate with the guys on the lake. This is her first IMU expedition, and I want it to be a good experience, especially so soon after losing her mother."

"I'm looking forward to meeting her," Katya said.

"The maintenance team thought the chopper would be grounded for another day. I'm hoping they'll get there soon enough for things to be up and running before we arrive. Last time we were diving was in Egypt a week ago. I've never dived in a central Asian lake. I'm looking forward to it."

"I might take a raincheck until I pa.s.s a Geiger counter over the water," Costas said, rubbing his stubble. "Forty-odd years of Soviet submersible and torpedo testing. I know exactly how they fueled their gear. It was my master's thesis at MIT."

"The biggest problem is the old Soviet early warning stations on the mountaintops, which were nuclear-powered so they could be left unmanned," Katya said. "Locals have raided them and come back with pockets full of uranium, and been dead within a week. The nightmare is that any of this stuff finds its way onto the black market. It's why the Americans are so keen to take over cleanup of the old naval base. It's not so much environmental concern, but the war on terrorism."

Jack thought he saw a flash of light in the distance. He glanced up at the boulder-strewn slope behind them. It could have been a reflection off gla.s.s or metal, or just a trick of the eye. He shaded his eyes against the sun, looking hard, then turned to Katya. "Anyone else out here?"

"The odd shepherd, sometimes a hunter who disappears up there and never seems to come back." She turned to Altamaty and spoke to him in Kyrgyz. He followed Jack's gaze up the ridge, then spoke quickly to Katya. "Altamaty has eagle eyes," she said. "He says he saw breath from a horse when it was cold early this morning, far up on the ridge. The hunters sometimes stay in one place for days, waiting for deer."

"You're sure it's a hunter?" Jack said.

Katya eyed him. "Who else do you think it could be?"

"Are you armed?" Costas asked.

"Altamaty has his old service Makarov pistol and an SKS rifle he liberated from navy stores here when the Soviet Empire collapsed. We go hunting together. It supplements the mutton that's the staple out here."

"I forgot," Costas murmured. "A palaeolinguist who knows about guns."

Katya gestured toward a cl.u.s.ter of boulders about fifty meters away, where the top of a tractor was just visible above the rocks. "Come on," she said. "The light's perfect now, just as it was yesterday when we found it. And Altamaty's got some stew simmering in a big pot outside the yurt. You're in for a traditional Kyrgyz feast this evening."

"I'm starving," Costas said. "And I know mutton's one of Jack's favorites." Jack gave him a withering look and swallowed hard. It was the one thing he had been dreading. He could stomach virtually anything, except boiled sheep. He had lived for several years as a child in New Zealand, and had once overindulged. Since then even the smell made him feel nauseous. He knew it was a matter of the utmost importance that he conquer the problem now. His manhood was at stake. He smiled at Altamaty, then followed Katya along a track between the boulders. The ground was hard, baked like brick, with only a few tufts of coa.r.s.e vegetation growing around the edge of the boulders. It was as if a sea of mud and rock had slid down the mountainside and solidified in one ma.s.s, embedding the boulders. Jack saw more rocks with carved designs on them, some so eroded they were barely discernible. He stopped for a moment to peer at one, and Costas hurried past him to Katya. "I meant to say," Costas said quietly, "I'm sorry about your uncle."

Katya glanced at him and nodded, saying nothing. She walked ahead, and they followed her in silence through the rocks until they came to the tractor. Costas stopped dead in his tracks, like a boy who had just been given a dream present. "A four sixty-five," he murmured reverently. "A Nuffield four sixty-five. This was why I got into engineering. I had a summer job on a farm in Canada. This was the first-ever diesel four-cylinder I disa.s.sembled." Altamaty opened the engine cowling, and the two men peered inside. Costas glanced at Jack. "I think I can bond with this guy. I think we just found a common language."

"No way," Jack said. "We did not come here to disa.s.semble a tractor." Costas sighed, patted Altamaty regretfully on the shoulder, then followed Jack to where Katya was kneeling in front of a boulder a few meters away. They could see where it had been dragged away by the tractor, revealing another boulder that had been partly buried. Between the two was a marked-off excavation area of about four by two meters. In the center was a carefully excavated pile of smaller rocks, about a meter across and two meters long. Jack squatted down and stared at the markings on the freshly exposed boulder. It was why Katya had called him here. "Well I'll be d.a.m.ned," he murmured.

"Another rock carving," Costas said. "It looks better preserved than the others."

"Not just another rock carving," Jack said. "It's fantastic." His mind was reeling. It was one thing hearing it on the phone from Katya, but another thing seeing it for real. He felt the power of the past as he touched it. Letters in Latin. "It's the same number as in the jungle shrine, the same symbol. XV Ap. The Fifteenth Apollinaris legion."

Costas knelt down beside Jack. "I can see it. And that Roman inscription from the cave in Uzbekistan. The one Katya's uncle recorded."

"It's definitely the same sculptor," Katya said. "I've photographed this and scanned it against the image from the cave. He has a distinctive way of doing his finials, ending each line by angling the chisel back and knocking out a triangular chunk of rock."

"A citizen-soldier," Jack murmured. "One who remembered his trade, and still practiced it with care. He was the one they called upon when they needed to make an inscription."

"In the cave in Uzbekistan, I think it was a casual marking, 'Licinius was here,'" Katya said. "Maybe the cave was where they really felt they had escaped from Merv, where the desert of Uzbekistan became the foothills of central Asia. From there, the Silk Route follows the ravines and mountain pa.s.ses that eventually lead to this place. But this inscription here by the lake was for a different reason. You can barely make out the first line above the legion inscription, but it's a different personal name, I think Appius. And look at those two letters at the bottom."

"D M," Jack said, tracing his fingers down. "Dis Manibus. That means given to Dis, the G.o.d of the underworld. A funerary inscription." He glanced at the pile of rocks between the boulders. "This is a grave."

Costas peered at the rock. "And that symbol above the inscription. It's an eagle, isn't it? Isn't that what we saw in the jungle shrine?"

"It's the same legion," Jack murmured. "Incredible."

"It's exactly what I dreamed we'd find," Katya said. "The burial place of someone who died here, or in the pa.s.s below. For some, this must have been a place for exultation, for recuperation before the next stage in the journey. For others, it would have been a place to die. There must have been many deaths among the traders, Persians, Bactrians, Sogdians, Chinese. But Roman? It's astonishing."

"Did you find anything in the grave?" Costas asked.

"It was a hasty burial, as you might expect," she replied. "The ground's rock-hard and there isn't enough wood here to fuel a cremation. The body was covered with stones, maybe cut turf That inscription would only have taken an hour or so to cut, for a skilled mason."

"A skilled mason?" Costas said. "Are you really sure about that?"

"There's no doubt about it." Jack traced his fingers over the symbols. "He had somehow fashioned a chisel with the right width of head, and he knew precisely where to place each blow. He knew the characteristics of this kind of rock, that it could take a glancing blow without fragmenting the surface. It's what I said in the jungle shrine. A citizen-soldier."

"You think this is the same guy?" Costas said.

"Let's wait to see what else Katya has to show us."

Katya looked at him, took a deep breath and pointed to a wooden finds crate on the ground. "The soil's very alkaline, and any bones would have disappeared long ago. But when the tractor dislodged the boulder, it revealed this." She drew back the cloth covering the interior of the crate.

Costas whistled. "That's some weapon." Inside was a magnificent socketed halberd-head, dull silver in color with patches of green where it had corroded. On one side was a vicious curved blade extending outward about ten inches, and on the other side a narrower straight blade, the shape of a cut-throat razor.

"I've seen one like that in the British Museum," Jack exclaimed. "Late Warring States, early Western Han period?"

Katya nodded. "The razor-shaped blade is similar in proportions to Han-period swords, which look like j.a.panese samurai swords."

"Isn't this bronze?" Costas said. "Wouldn't that be too early for us?"

Katya shook her head. "Not necessarily. Iron was introduced in China by the fifth century BC, but the early cast iron was brittle so bronze was still used. And this bronze has been coated with chromium, which would have made it harder, better to hold a sharp edge."

"And a weapon like this might have been prized, pa.s.sed down the generations," Jack murmured, touching the blade. "It could have been made in the early Han period, not long after the time of the First Emperor. But it could have survived in use for two centuries or more, to the period when we think these Romans came here."

"But what's a prestigious Chinese weapon doing in this place?" Costas said. "A pa.s.sing Imperial Chinese warrior dumps it on a Roman grave? I don't get it." He gazed at Katya, who stared back at him, her eyes gleaming. "Ah," Costas said. "That's uncannily like the look Jack gives me. It means you've found something else."

Katya picked up a small plastic finds tray from beside the crate. "The halberd was in the center of the grave, as if it had been placed on the torso of the body. These two objects were where the head might have been." There were two coins in the tray, one silver and one corroded green, a disk with a square hole in the center. Jack took the silver coin, holding it up in the fading sunlight. "It's a silver tetradrachm of Alexander the Great!"

"And it's uncirculated," Katya said. "It's like those Roman coins from south India you were telling me about, uncirculated bullion."

Jack pa.s.sed the coin to Costas. They could see the portrait on the obverse, the familiar head of Alexander wearing the mane of a lion, the cla.s.sical form giving sudden reality to the idea of travelers from the ancient Graeco-Roman world coming this far east, to the very borderlands with China. Costas rotated the coin, peering at the portrait again, and a puzzled look returned to his face. "If my history's right, Alexander the Great lived in the later fourth century BC. That's a hundred years before the First Emperor, and three hundred years before our Romans. There must have been old Greek coins that found their way out here, used as bullion, jewelry. But they would have been worn." He looked dubiously at the Latin inscription on the boulder, then back at the coin. "Does this mean we're not looking at a Roman here after all, but at a soldier of Alexander the Great?"

"You've read the Periplus of the Erythraean Sea?" Katya said.

"The merchant's guide? First century BC, Egyptian Greek. I'm becoming an expert."