Next, from the sinkhole’s south rim, Painter watched the ruins of the citadel, perched precariously over the western edge, begin a slow tumble into the pit. And at the bottom, lit by the balefire flames as they petered out, two figures stumbled across the floor, rocks falling all around them.

Safia and Omaha.

11:22 A.M.

DAZED, OMAHAleaned on Safia. She had an arm under his shoulders. They fought through the sands. His eyes wept from the residual burn on his retinas, but vision slowly returned. First a glow formed, dull, bluish. Then he saw dark shadows falling around him, thudding into the sand, some bouncing.

A rain of rocks. A biblical curse.

“We must get clear!” Safia yelled, sounding as if she were underwater.

Something struck the back of his good leg. They were both thrown to the sand. A deep grumble rattled behind them, above them, an angry god.

“It’s coming down!”

11:33 A.M.

PAINTER RACEDheadlong down the path into the sinkhole.

To his left, the back half of the citadel spilled into the chasm. It groaned and rumbled. Pouring rock and sand into one end of the pit. Painter had witnessed a mud slide during a rainstorm, an entire hillside liquefying. This was the same. Only a bit slower. Rock proving more stubborn.

In snatches through the stormy gloom, he spotted Safia and Omaha scrambling away from the avalanche as it slowly spilled toward them, chasing them across the floor. They fell down again as Omaha was struck in the shoulder and spun around.

Painter would not reach them in time.

A throaty growl whined behind him and a shout: “Out of the way!”

The shout threw him around. A light flicked on, spearing him in the face. He was blinded, but he saw enough in that split second to dive aside.

The sand bike sailed passed him down the slope, spewing up gravel and sand. It leaped the path ten feet from the bottom, front wheel yanked up, rear knobby wheel spinning. It landed with a bounce, a twist, a crunch of sand-then tore off across the floor.

Painter continued down the path.

He had spotted the rider, bent over the handlebars. It was Coral Novak, cloaked and goggled, hood thrown back, white hair flagging behind her.

Painter gave chase, watching the cycle tear alongside the avalanche. Its headlamp flicked back and forth as Coral dodged around obstacles. Then she reached the pair, braking and skidding to them. He heard her shout.

“Grab tight!”

Then she was off again, shooting straight across the floor, away from the tumbling stones, hauling Omaha and Safia, who clung to the seat’s back, feet and legs dragging behind.

They raced clear of the rock slide.

Painter reached the bottom, well clear of the tumult of stone and sand. By the time he reached the floor, it was over. The collapse of the hill and fortress settled to a stop. The steep cliff was now a gentle slope.

Edging the wide delta of spilled rock and sand, Painter hurried to the idling bike. Safia had climbed to her feet. Omaha leaned one hand on the seat. Coral sat astride the bike.

They all stared at the hole in the ground ahead of them. It steamed and roiled, like some entrance to hell. It was where the trilith chamber had once opened. Only now it was ten feet across, blasted wide.

And bubbling with water.

The headlamp of the bike illuminated the steaming surface.

As Painter watched, the waters receded, draining away rapidly.

What was revealed held everyone silent.

11:23 A.M.

CASSANDRA STARED,unblinking, through the windshield of the M4 tractor. A minute ago, they had watched a blue flash of fire shoot skyward. It had come from straight ahead.

In the direction of the ruins.

“What the hell was that?” Kane asked from the driver’s seat.

They had halted the tractor a hundred yards off. To the left, the town flickered with a dozen fires. Directly ahead, the ruins had gone dark again, lost in the storm.

“That was not one of our bloody mortars,” Kane said.

It sure as hell wasn’t. Cassandra glanced to her laptop. The glow of the curator’s transceiver continued to shine, though now it flickered, as if some interference fluttered its signal. What was going on over there?

She attempted to radio the only person who might know. “Eagle One, can you read me?”

She waited for a reply. None came.

Kane shook his head. “Both birds are down.”

“Order another two copters in the air. I want aerial coverage.”

Kane hesitated. Cassandra knew his concern. The storm, while already blowing fiercely, was only beginning to ratchet up. Its full might had yet to strike. And the coastal weather system was rushing up from the south, promising even wilder weather to come as the two systems collided. Outfitted as they were with only six VTOL copter sleds, to send up another pair risked half their remaining aerial force.

But Kane understood the necessity. They dared not conserve their resources. It was all or nothing. He passed Cassandra’s orders over his own radio. Once done, he glanced to her, silently asking her how to proceed.

She nodded ahead. “We’re going in.”

“Should we wait until the birds are in the air?”

“No, we’re armored.” She glanced over her shoulder to the men seated in the back compartment, Kane’s commando team. “And we have enough land support with us. Something’s happening over there. I can smell it.”

He nodded, shifted into gear, and kicked the tractor into motion. The lumbering tank ambled toward the ruins.

11:26 A.M.

SAFIA KNELTon one knee and reached a hand over the hole’s lip. She tested the heat with her palm. Winds tugged at her. Sand swirled in sweeps, but not as fiercely. The storm had abated slightly, a momentary pause, as if the explosion had sapped some strength from the gale’s force.

“Careful,” Omaha said behind her.

Safia stared down the hole at her feet. The waters continued to recede. It seemed impossible. As the waters had drained away, a glass ramp revealed itself, spiraling deep. The trilith chamber was gone. All that was left was glass, flowing downward in a corkscrew.

The entrance to Ubar.

Safia lowered her palm toward the ramp’s exterior, slowly, bringing it close to the glass. It still glistened with drops of water, radiant against the black surface, reflecting the bike’s headlight.

She felt no searing burn.

Daring, Safia touched a finger to the black glass. It was still warm, very warm, but it didn’t burn. She placed her palm flat. “It’s solid,” she said. “Still cooling, but the surface is hard.” She rapped on it to demonstrate.

Standing up, she reached a leg out and placed a foot on the ramp. It held her weight. “The waters must have cooled it enough to harden.”

Painter stepped toward her. “We’ve got to get out of here.”

Coral spoke, still astride her bike. She lowered the radio from her lips. “Commander, all Rahim are now gathered. We can bug out on your word.”

Safia turned to the upper rim, but it was lost in darkness. She glanced down the throat of the glass spiral. “This is what we came to find.”

“If we don’t leave now, Cassandra will bottle us here.”

Omaha joined them. “Where will we go?”

Painter pointed west. “Into the desert. Use the storm as cover.”

“Are you mad? This blow is just starting. And the worst is yet to come. What about that goddamn megastorm? Out in the open desert?” Omaha shook his head. “I’d rather take my chances with that bitch.”