Safia crossed to her. “No human remains were ever found in or around the sinkhole. She must have found some way to clear the city. A ceremony or something. Then sank the hole. I doubt anyone died here.”

Still, the hodja was unconvinced, even taking a step back from Safia.

A shout rose from the diggers. “We found something!” Danny yelled.

All their faces turned to him.

“Come see before we dig further.”

Painter and the others all shifted over. Coral and Clay stepped aside for them. Danny pointed his shovel.

In the center of the trenchlike hole, the dark red sand had turned to snow.

“What is that?” Kara asked.

Safia hopped down, dropped to a knee, and ran her hand over the surface. “It’s not sand.” She glanced up. “It’s frankincense.”

“What?” Painter asked.

“Silver frankincense,” Safia elaborated, and stood up. “The same as what was found plugging the iron heart. An expensive form of cement. It’s stoppered the top of the hidden chamber like a cork in a bottle.”

“And below it?” Painter asked.

Safia shrugged. “There’s only one way to find out.”

9:45 A.M.

CASSANDRA CLUTCHEDher laptop as the M4 high-speed tractor mashed over another small dune. The transport vehicle looked like a brown Winnebago balanced on a pair of tank treads, and despite its eighteen-ton weight, it chewed across the landscape with the efficiency of a BMW down the Autobahn.

She kept the pace reasonable, respecting the terrain and weather. Visibility was poor, only yards ahead. Windblown sand flumed all around, whipping off the tops of dunes in vast sails. The sky had darkened, cloudless, the sun no more than a wan moon above. She dared not risk bogging down the tractor. They’d never drag it free. So they proceeded with sensible caution.

Behind her the other five all-terrain trucks traveled in the tracks of the larger tractor as it blazed a trail through the desert. In the rear were the flatbeds with the cradled VTOL copters.

She glanced to the clock in the corner of the laptop’s screen. While it had taken a full fifteen minutes to get the caravan moving, they were now making good time. They’d reach Shisur in another twenty minutes.

Still, she kept an eye on the screen. Two display windows were open on it. One was a real-time feed from an NOAA satellite that tracked the path of the sandstorm. She had no doubt they’d reach the shelter of the oasis before the full storm struck, but just barely. And of even greater concern, the coastal high-pressure system was on the move inland, due to collide with this desert storm in the next few hours. It would be hell out here for a while.

The other screen on the monitor displayed another map of the area, a topographic schematic of this corner of the desert. It diagrammed every building and structure in Shisur, including the ruins. A small blue spinning ring, the size of a pencil eraser, glowed at the center of the ruins.

Dr. Safia al-Maaz.

Cassandra stared at the blue glow. What are you up to? The woman had led her off course, away from the prize. She thought to steal it out from under Cassandra’s nose, using the cover of the storm. Smart girl. But intelligence carried you only so far. Strength of arm was just as important. Sigma had taught her that, pairing brawn and brain. The sum of all men. Sigma’s motto.

Cassandra would teach that lesson to Dr. al-Maaz.

You may be smart, but I have the strength.

She glanced to the side mirror, to the trail of military vehicles. Inside, one hundred men armed with the latest in military and Guild hardware. Directly behind, in the tractor’s transport bed, John Kane sat with his men. Rifles bristled as they performed the deadly sacrament of a final weapons inspection. They were the best of the best, her Praetorian guards.

Cassandra stared ahead as the tractor ground its way inevitably forward. She attempted to pierce the gloom and windswept landscape.

Dr. al-Maaz might discover the treasure out there.

But in the end, Cassandra would take it.

She glanced back to the laptop’s screen. The storm ate away the map of the region, consuming all in its path. On the other display window, the schematic of the town and ruins glowed in the dim cabin.

Cassandra suddenly tensed. The blue ring had vanished from the map.

Dr. al-Maaz was gone.

9:53 A.M.

SAFIA HUNGfrom the caving ladder. She stared up at Painter above. His flashlight blinded her. She flashed on the moment in the museum when she hung from the glass roof and he was below her, encouraging her to wait for security. Only now their roles were reversed. He was on top; she was below. Yet once again, she was the one hanging above a drop.

“Just a few more steps,” he said, his scarf whipping about his neck.

She glanced to Omaha below. He held the ladder steady. “I got you.”

Bits of crumbling frankincense cascaded around her. Boulders of it lay around Omaha’s feet, and the air in the subterranean chamber was redolent with its aroma. It had taken only a few minutes with pickaxes to perforate into the conical-shaped cave.

Once they had broken through, Omaha had lowered a candle into the cave, both to check for bad air and to light the interior. He then went down the collapsible ladder, inspecting the chamber himself. Only when he was satisfied did he let Safia climb down. With her injured shoulder, she had to loosen her left arm from her sling and carry most of her weight with her right.

She struggled the rest of the way down. Omaha’s hand found her waist, and she leaned into his grip gratefully. He helped her to the floor.

“I’m all right,” she said when he kept a hand on her elbow.

He lowered his hand.

It was much quieter out of the wind, making her feel slightly deaf.

Already Painter had mounted the ladder, coming down, moving swiftly. Soon three flashlights shone across the walls.

“It’s like being inside a pyramid,” Painter said.

Safia nodded. Three rough walls tilted up to the hole at the top.

Omaha knelt on the floor, running his fingers across the ground.

“Sandstone,” Safia said. “All three walls and floor.”

“Is that significant?” Painter asked.

“This is not natural. The walls and floor are hewn slabs of sandstone. This is a man-made structure. Built atop bedrock of limestone, I imagine. Then sand was poured around the outside. Once it was covered, they plugged the hole at the top and covered it with more loose sand.”

Omaha stared up. “And to make sure no one found it by accident, they dropped the sinkhole atop it, frightening everyone away with ghost stories.”

“But why do all that?” Painter asked. “What’s this supposed to be?”

“Isn’t it obvious?” Omaha grinned at him, looking suddenly striking to Safia. His goggles lay draped under his chin, his scarf and hood thrown back. He had not shaved in a couple of days, leaving a bronzed stubble over cheek and chin, his hair stuck up in odd places. She had forgotten how he looked in the field. Half wild, untamed. He was in his natural element, a lion on the veldt.

All that came to her with only the flash of his grin.

He loved all this-and once, she had, too. She had been as wild and uninhibited, his companion, lover, friend, colleague. Then Tel Aviv…

“What’s obvious?” Painter asked.

Omaha flung an arm. “This structure. You saw one of these today.”

Painter frowned.

Safia knew Omaha was teasing this out, not from malice, but simply from pure enjoyment and awe.

“We banged into one of these-a much smaller one-as we descended out of the mountains.”

Painter’s eyes widened, his gaze swept the space. “Those prayer stones.”

“A trilith,” Omaha said. “We’re standing inside a giant trilith.”