Miyuki made a noncommittal noise. She kept glancing back over her shoulder as they moved slowly down the stairs. “Do you think they’ll follow?”

Karen directed her light forward again. “I…I don’t know. But if they do, let’s be as far away from here as possible.”

Miyuki was silent for several steps. Her breathing, though, was strained and tight. She finally asked the question uppermost in Karen’s mind. “Where do you think this leads?”

“I’d guess some royal burial chamber. But I’m not sure. This passage is pretty steep. We must be close to the base of the pyramid by now.”

Proving her theory true, the stairs ended at a tunnel. The next passage led in a straight line away from there. A long way. Karen’s light failed to find an end. She assumed the tunnel led beyond the pyramid itself.

Frowning, she moved down to the last step. Ahead, the tunnel lay partially flooded. At least a foot of water covered the floor. Within the beam of her light, Karen watched trickles of water drip and flow from cracks in the ceiling. “We must be underneath the pyramid…underneath the sea itself,” she muttered. “Look at the walls here. They’re not carved stone blocks, but solid rock. It must have taken decades to tunnel out this passage.”

Miyuki leaned beside her. “Maybe not. It might just be a lava tube. Japan is riddled with them.”

“Hmm…maybe.”

Miyuki stared over at the dripping water. “I don’t know about this. Can’t we just wait—”

A ringing sound cut her off, echoing down the stairs to them. Metal on rock. The two women’s eyes met.

“They’re trying to dig themselves inside,” Karen said.

Miyuki pushed Karen toward the watery passage. “Get going!”

Karen splashed into the water and gasped as the cold clamped around her ankles. The tang of salt was sharp in the stagnant air. Miyuki followed, holding her equipment bag tight. They continued down the long tunnel, their splashes echoing up and down the passage. The noise made them both edgy.

Karen ran her fingers along the wall here, too. It was still smooth, almost glassy. Too smooth to have been carved by crude tools. It seemed a natural passage, as Miyuki had suggested. She tapped the wall with a knuckle.

“Don’t do that!” Miyuki yelled at her.

The shout startled Karen. She dropped her hand.

“Do you want to drown us?” Miyuki said.

“This passage has been down here for ages.”

“Still, don’t knock on the walls. After the quakes and uplift, you don’t know how fragile it might be.”

“All right,” Karen said, “I’ll leave it alone.” She turned her attention to the passage ahead, which seemed to widen. She increased her pace. Could it be the end? She prayed for another exit. The ringing strike of metal on stone still echoed periodically behind them. Their pursuers were not giving up.

Splashing in water up to her knees now, Karen hurried forward, then stopped. She looked around, mouth gaping open. The passage continued, but here the tunnel ballooned out. The ceiling became a dome overhead, as glassy and smooth as the passage itself. If this was a lava tube, a bubble must have formed at this spot.

Karen wagged her flashlight around. Overhead, embedded bits of glittering quartz dotted the roof. At first she thought it was a random pattern, then she turned in a circle, neck craned back. “It’s a starscape. See, there’s the Orion constellation.”

Miyuki looked less impressed. She glanced over her shoulder as another echoing strike sounded behind them. “We should keep going.”

Karen lowered her light. She knew Miyuki was right, but her legs would not move. Nothing like this had ever been discovered among the islands of the South Pacific. Who had built this? Her light, now pointing forward, settled on a waist-high section of the wall. A sharp glint attracted her attention. She narrowed her eyes. A small niche had been dug out of the smooth wall. A cubbyhole. Something inside reflected back her light. Karen approached it.

Miyuki started to speak, but Karen stopped her with an upraised hand. She bent to peer into the tiny alcove. Resting inside was a palm-size crystal star. Five points glittered brightly under her penlight. It was as if a rainbow had exploded inside. As she shifted her light, she noticed deep scratches on the nearby wall and took a step back. She had almost missed it at first. She cast her light along the curved wall.

“My God!”

Meticulously carved into the stone were lines of small symbols. Three rows of them. Clearly some form of archaic language.

Bending closer, she touched the first symbol with a finger. The wall etchings were precise, carved deep, as if written with a diamond-pointed tool. But for all the precision, the symbols themselves were crude. Rough hieroglyphics. Pictures of animals and men in distorted shapes and postures. Strange icons and repeated symbols.

Karen tilted her head, moving the light. The rows continued, waist-high around the bubble in the tunnel.

She turned to Miyuki, her breath rushed. “I need a picture of this.”

“What?” Her friend looked at her as if she were crazy.

Karen straightened, reaching for Miyuki’s bag. “Video record it. Save it. I can’t risk this being lost.”

Miyuki scowled. “What are you thinking? We need to get out here.”

“The looters might destroy this. Or the whole area might sink again.”

“I’m more worried about it sinking with us in it.”

Karen pleaded with her eyes.

Finally, Miyuki sighed and passed the satchel to Karen, who held it as Miyuki shuffled through it for her tiny digital camera. Freeing it, she passed Karen her own larger flashlight. “I’ll need plenty of light. Follow as I record.” Miyuki returned to the wall, camera raised. She slowly edged around the chamber, tracing the wrap of ancient writing until she made a complete circuit.

Karen realized something as they worked. “It’s not three rows,” she mumbled. “It’s one continuous line — starting at the crystal star and wrapping around and around the room, like the groove in a vinyl record.”

“Or a curled snake,” Miyuki said, lowering the camera as she finished recording. She started to put it away. “Satisfied?”

Karen passed Miyuki the large flashlight. “Could you get a couple shots of the star map on the ceiling?”

Miyuki frowned but took the flashlight.

Snugging the equipment satchel over her shoulder, Karen turned away. “I’m going to take the crystal artifact with me. We can’t let the looters get it.” She crossed to the cubbyhole and reached inside, grabbed the star and tried to pick it up, but failed. She gave it a cautious tug, but it didn’t budge. “Goddamn. It’s cemented in place.”

Finished with the recording, Miyuki joined Karen. “Then leave it.” She peered down the tunnel. The sound of digging had stopped a few minutes ago. “I don’t like this quiet. Maybe they got through.”

Karen scrunched up her brow. She didn’t want to leave the crystal star behind. “Shine your light in here so I can see what I’m doing.”

Miyuki moved closer and shone her light into the cubby. Again the rainbow brilliance sparked sharply. “It’s beautiful,” she conceded in a hushed voice.

Again Karen palmed the star and tugged hard. This time it popped free easily. Caught off guard, she stumbled back, bumping into Miyuki. Her friend’s flashlight went flying and splashed into the water.

Miyuki bent to retrieve it. “I hope you’re done,” she said, fishing through the seawater. “Lucky the flashlight’s waterproof.”

Karen held the star against her belly. It was like cradling a bowling ball. She had to hold it with both hands. The star hadn’t been cemented into the niche, she simply hadn’t expected it to be so heavy. “This thing weighs a ton,” she said. She lifted the star and dropped it into a side pocket of the equipment bag. The bag now pulled hard on her shoulder. “Okay. Let’s keep going.”