“But what type? Quartz?”

Charlie tilted his head, watching the video. “No. That’s just it. I don’t know. At least not yet. But I’d sell the Fathom for a sliver of it.”

“So you think it’s something new?”

The tall Jamaican nodded. “Nowhere on this planet is there an environment like the one down there.” Charlie tapped at the screen. The sub slowly circled the spire, showing the brilliant shaft from every angle. The video image was crisp and detailed. Flawless. There was no sign of the interference that was described topside. “At these extreme pressures of seawater and salinity, who knows how crystals might grow?”

Jack sat on one of the stools. He leaned closer to the screen. “So what you’re saying is that we’re the first people ever to see such a crystal creation?”

Charlie laughed, drawing Jack’s eye away from the screen. “No. I’m not saying that, mon…I’m not saying that at all.” Charlie manipulated the remote’s shuttle, slowing the recording.

Jack watched the spire slow its spin as the submersible finished its circuit. Charlie stopped the video just as the sub’s xenon headlamps began to swing away. Jack remembered this was the moment when he had turned back to continue his search for the black boxes. He had been looking elsewhere and missed what his camera picked up next.

With the light cast at an angle across the nearest plane of the obelisk, slight imperfections could be seen marring its crystalline surface.

“What is that?”

“Proof that we’re not the first to discover this crystal.” Charlie played with the remote and zoomed in on the imperfections. The image swelled on the monitor. The imperfections grew into rows of tiny markings, too regular and precise to be natural. Jack leaned in closer. Though the enlarged video image was fuzzy, there was no mistaking what he was seeing.

George spoke it aloud, voice hushed with awe. “It’s writing. Some type of ancient inscription.”

“But at those depths?” Jack stared in disbelief. Etched deep into the crystal were blocks and rows of tiny iconlike images: animals, trees, distorted figures, geometric shapes.

Jack could not dismiss what he was seeing. Each symbol was carved into the smooth surface, then filled with a shiny metallic compound. It was no optical illusion.

It was ancient writing…on a spire two thousand feet underwater.

Off the coast of Yonaguni Island, Okinawa Prefecture

Karen held her penlight above her head as she fought the growing depth of the water. She slogged forward, the water now past her waist. She shrugged the equipment bag higher on her shoulder, trying her best to keep it dry, but the heavy weight kept pulling toward the rising seawater. When would this passage end? How long was it? Up and down the passage the echo of pouring water filled the tunnel.

Behind her, she could hear Miyuki struggling. The Japanese professor was smaller than her, the water up to Miyuki’s breasts. She half swam to keep up.

At last Karen saw her penlight illuminate another wall ahead, something different than this endless passage. “I think we’ve reached the end.”

She moved faster. The tunnel ended at a staircase, its steps climbing up. It reminded her of the staircase that had led them down here. She reached the first step, almost trip-ping over it since it was under the black water. Catching herself on the smooth wall, Karen stumbled up the steps and dragged herself out of the flooding passage.

She turned to help Miyuki, and both women climbed several steps until exhaustion dragged them down. They sat on the dry stairs, panting, shivering.

Karen pointed to the walls on either side. “Stone blocks,” she said. Here the walls and ceiling were no longer bare rock, but stacked and carefully fitted basalt slabs and blocks. “We’re above the lava tube.”

“So we won’t drown?” Miyuki looked pale, her ebony hair wet and clinging to her face.

“Not if we climb high enough. Get above sea level.”

Miyuki stared up the staircase. “But where are we?”

“If I had to guess, I’d say these steps lead into the heart of the second Dragon, the twin pyramid to the one we entered.” At least, she hoped so. But it made some sort of symmetrical sense. And if she wasn’t mistaken, the passage had been heading in the direction of the other pyramid. The lava tube must connect the two structures.

“Will there be a way out?”

Karen nodded. “I’m sure there is.” She left unspoken her own fear. What if they couldn’t find it?

“Then let’s go,” Miyuki said, shoving herself to her feet. She reached toward Karen. “I’ll carry the bag from here.”

Karen pushed the strap off, only too glad to shed the burden, and passed the bag to Miyuki, who almost dropped it.

“You weren’t kidding that it’s heavy,” she said, straining to heft it to her own shoulder.

“Nope. It’s that crystal artifact. It must weigh close to ten kilos.”

“But it was so small.”

Karen shrugged and stood up. “Just one more mystery about this place.” Sighing, she led the way up, praying that the final mystery would not escape her: the way out of this death trap.

The climb up the steep stairs was a cruel torture for their aching limbs. It felt like they were climbing a ladder. But they plodded onward, silent, too tired to talk. At least the exertion served to warm their cold bodies. But soon even the warmth became a burden. With each step the temperature seemed to rise in the narrow stairway. By the time they neared the top of the stairs, it was stifling. It seemed to Karen that her damp clothes were steaming.

She wiped the sweat from her forehead and entered the next chamber. “Finally,” she moaned as she shuffled into the room. Miyuki followed her, wheezing. Karen raised her small flashlight.

The bare walls of the inner chamber offered no clue to an exit. Stacked stones and a slab roof surrounded them. Both women gazed around. There were no adornments, no writing.

Karen moved along the margins of the walls. “Turn off your light,” she ordered Miyuki. Karen flicked her penlight off, too.

Darkness plunged around them. The echo of splashing water from the passage below seemed to swell. With eyes wide, Karen looked for a chink in the solid walls and ceiling. Some evidence of an exit. By now she assumed the sun would be sliding toward the western horizon.

She mopped at her brow. It was so warm in there. Not a bit of air moved. With one hand on a wall, she edged around the room, searching for a telltale glow, some sign of an exit. But the darkness seemed complete.

“Are you finding anything?” Miyuki asked, hopeful.

Karen had opened her mouth to answer when her hand touched a stone warmer than the others. She paused, placing one palm on one stone and the other on its neighbor. There was a clear difference in temperature.

“I think I may have a clue here.” She fingered the edges of the warmer stone. It was difficult in the dark. The blocks had been fitted snugly. She discovered the edges, but as she stared, found no sign of sunlight creeping through. She frowned. There had to be a reason for the warmer stone.

Karen thumbed on her penlight, and Miyuki moved to her side, resting her bag on the stone floor. She rubbed at her shoulder. “What did you find?”

Karen shoved hard on the stone. It didn’t move. She backed up a step, head tilted, studying the stone block. It was featureless, about half a meter square. “This is warmer than the others, suggesting it must be more directly exposed to the sun.”

“Is it a way out?” Miyuki turned on her own flashlight.

“I hope so. I just don’t know how to open it.” Karen closed her eyes. Think, goddamn it! She pictured the second Dragon in her mind. It was identical to the first, except for the collapsed temple. This second pyramid’s summit had been bare. No clue.

“What are you thinking?” Miyuki asked.

Karen opened her eyes. “I’m not sure. In the other pyramid, the temple’s altar was the access point. The sculptured snake head was the key.”

“Yeah?”

“Think symmetry. Think larger. In the ruins of Chichen Itza on the Yucatan peninsula, the main pyramid casts a snake shadow during the equinoxes, a winding shadowy body that connects to a carved stone snake head at its base.”

“I don’t understand.”

Karen kept talking, intuiting that she was close to an answer. “The serpent’s head was the entry point. This connected to a long lava tube…perhaps representing a snake’s body.”

Miyuki nodded. “If you’re right, then we’re in the snake’s tail.”

“We were swallowed by a snake, traveled through its belly, and now must complete the digestive process.”

“In other words, we must find this snake’s butt.”

Karen laughed at the dead seriousness with which Miyuki had spoken these last words. “Yep.” Karen turned. The opening to the stairwell lay directly opposite her. She twisted around. The warm stone was in direct line with the opening. A straight line. She placed a hand on the stone. “This is the tip of the tail. The end of the snake.”

“Right. You said that. It’s the way out.”

“No! We aren’t paying attention to anatomy. A snake’s butt isn’t in the tip of its tail. It’s on its underside!” Karen pointed to the floor. “Its belly!”

Miyuki stared at her toes. “To go up, we must go down.”

Karen dropped to her knees on the stone floor. It wasn’t a slab, but fitted blocks, like the walls. She crawled forward, starting at the warm brick and aiming for the stairwell, wiping the water and debris from the floor as she went. It had to be here!

Her fingers brushed over something rough on the smooth stone. She froze for a heartbeat, then rubbed the spot, praying.

Miyuki knelt near her. “What is it?”

Karen moved aside. “The snake’s butt!”

Imprinted into the smooth block was a carving: a star-shaped depression.

“Get me the crystal!”