“And below it?” Painter asked.

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

9:45 A.M.

C ASSANDRA CLUTCHED her laptop as the M4 highspeed 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.

S AFIA HUNG from 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.”

Safia suspected Omaha wanted to jump up and down, and truth be told, his excitement was contagious. She could not stand still herself. “We need to bring the keys down here.”

“What about the storm?” Painter cautioned.

“Screw the storm,” Omaha said. “You and the others can go and hide out in town. I’m staying here.” His eyes fell on Safia.

She nodded. “We’ve good shelter here. If someone could lower the iron artifacts, water, a few supplies, let Omaha and me figure out what to do with them. We might have the riddle solved by the time the worst of the storm blows itself out. Otherwise, we’ll lose a whole day.”

Painter sighed. “I should stay here, too.”

Omaha waved him off. “Crowe, you’re not much use to us. To use your own words from earlier, this is my area of expertise. Guns, military ops…that’s you. Here, you’re simply taking up space.”

Storm clouds built behind Painter’s blue eyes.

Safia placed a conciliatory hand on the man’s arm. “Omaha’s right. We’ve got radios if we need anything. Someone has to make sure everyone stays safe when the storm hits.”

With clear reluctance, Painter stepped to the ladder. His eyes lingered on her, glanced to Omaha, then away. He climbed up and called back. “Radio what you’ll need.” He then shooed everyone away, herding them back to the shelter of the cinder-block homes.

Safia suddenly became acutely aware of how alone she was with Omaha. What had seemed so natural a moment ago now seemed strange and uncomfortable, as if the air had suddenly soured in here. The chamber felt too cramped, claustrophobic. Maybe this wasn’t such a brilliant idea.

“Where do we start?” Omaha asked, his back to her.

Safia lifted her arm back into her sling. “We look for clues.”

She stepped away and shone her light up and down each wall. Each appeared to be the identical size and shape. The only mark was a small square hole cut halfway up one wall, perhaps a place to rest an oil lamp.

Omaha lifted a metal detector from the floor.

Safia waved him to put it down. “I doubt that’s going to—”

As soon as he flipped on its power, the detector pinged. Omaha’s eyebrows rose. “Talk about beginner’s luck.”

But as he swept the device over more of the floor, the detector continued its pinging, as if the metal lay everywhere. He lifted it to the sandstone walls. More pinging.

“Okay,” Omaha conceded, dropping the detector, getting nowhere. “I’m beginning to really hate that old queen.”

“She’s hidden a needle in a haystack.”

“All this must have been too deep for the surface detectors. Time to go low-tech.” Omaha pulled free a notepad and pencil. With compass in hand, he began mapping out the trilith. “So what about those keys?”

“What about them?”

“If they’re from the time of Ubar’s downfall, how did they end up in a statue from 200 B.C.? Or at Job’s tomb? Ubar fell in A.D. 300.”

“Look around you,” Safia said. “They were skilled artisans in sandstone. They must have found those holy sites, balanced whatever energy source lies within these keys. Antimatter or whatever. And burrowed the artifacts into elements already at the tombs: the statue in Salalah, the prayer wall at Job’s tomb. Then they sealed them over again with sandstone with a skill that left their handiwork undetectable.”