“From the first riddle,” Monk answered. “You know. The painted fish in the catacombs.”
“What about it?”
“I can see you guys and the statue through the Aqua-Vu camera. The sphinx is facing toward that big fort.”
Gray stared at the statue. From here, where visibility was no greater than five yards, it was hard to get the bigger picture. Monk had the better perspective. And the bigger picture was his area of expertise, seeing the forest through the trees.
“The catacombs…” Gray mumbled, understanding Monk’s intent.
Could it be that easy?
“Remember,” Monk continued, “how we had to follow the direction the fish was facing to find our next clue? Maybe the sphinx is facing toward the tunnel opening.”
“Monk could be right,” Vigor said. “These clues were planted in the early fourteenth century. We should be considering the problem from the perspective of that era’s level of technology. They didn’t have scuba gear at the time. But they did have compasses. The sphinx may be nothing but a magnetic road marker. You use your compass to find it. Swim down to take a peek at where it’s facing and move onto shore.”
“There’s only one way to find out,” Gray said. “Monk, keep the boat anchored here until we’re sure. We’ll swim toward shore.”
Gray kicked away from the statue. He waited until he was far enough away to get a good compass fix without the magnetic interference of the lodestone. “Okay, let’s see where this leads.”
He set off. The others trailed behind him. They stuck close together.
The shore was not far. The spit of land rose steeply. The sandy bottom ended abruptly at a tumbled maze of stone blocks. Man-made.
“Must have once been a section of the Pharos Lighthouse,” Vigor said.
Barnacles and anemones had taken over the area, forming it into their own reef. Crabs scrabbled and tiny fish darted.
“We should spread out,” Kat said. “Search the area.”
“No.” Gray intuitively understood what needed to be done. “It’s like the magnetic sphinx hidden among the other sphinxes.” He kicked off the bottom, traveling up the reefscape. He kept one arm fixed in front of him, watching the wrist compass.
It didn’t take long.
Passing over one block, his compass needle pitched and rolled. He was only four yards from the surface. The front of the block was about two feet square.
“Here,” he said.
The others joined him.
Kat took a blade and scraped off the accumulation of sealife. “Hematite again. Less strongly magnetic. You’d never notice it unless you were looking for it.”
“Monk,” Gray said.
“Yeah, boss.”
“Bring the boat over here and drop anchor.”
“On my way.”
Gray searched the edges of the block. It was cemented to its neighbors—above, below, and to the sides—by coral, sand, and dense accumulations of rough-shelled mussels.
“Everyone pick a side and dig the edges clear,” he ordered. He pictured the hematite slab under Saint Peter’s tomb. It had covered a secret tunnel. He had no doubt that they were on the right track.
For once.
In a couple of minutes, the block was cleared.
The beat of a propeller echoed leadenly through the water.
Monk approached the shoreline slowly. “I can see you guys,” he said. “A bunch of striped frogs sitting on a rock.”
“Lower the anchor,” Gray said. “Slowly.”
“Here it comes.”
As the prong of heavy steel dropped from the keel, Gray swam over and helped guide it to the hematite block. He jammed a corner into a gap between the block and its neighbor.
“Winch it up,” Gray ordered.
Monk retracted the anchor line. It grew taut.
“Everybody back,” Gray warned.
The block rocked. Sand billowed from it. Then the chunk of stone tipped loose. It had only been about a foot thick. It rolled down the cliff face, bouncing with muffled crashes, then landed heavily on the sandy floor.
Gray waited for the silt to clear. Pebbles continued to rain down the wall of rock. He moved forward. In the gap-toothed opening left by the dislodged stone, a dark space loomed.
Gray flicked on the flashlight on his wrist. He pointed it into the opening. The light illuminated a straight tunnel, angled slightly upward. It was a tight squeeze. No room for air tanks.
Where did it lead?
There was only one way to find out.
Gray reached to the buckles securing his air tank. He shimmied out of them.
“What are you doing?” Rachel asked.
“Someone’s got to go take a look.”
“We could unrig the boat’s Aqua-Vu camera,” Kat said. “Use a fishing pole or an oar to push the camera inside.”
It wasn’t a bad plan—but it would take time.
Time they didn’t have.
Gray settled his tank to a shelf of rock. “I’ll be right back.” He took a deep breath, unhooked the regulator hose from his mask, then turned to face the tunnel.
It would be snug.
He remembered the riddle of the Sphinx. How it described the first stage of man. Crawling on all fours. It was a fitting way to enter.
Gray ducked his head, arms forward, flashlight leading. He kicked off and sailed into the cramped tunnel.
As the tunnel swallowed him up, he remembered Vigor’s earlier warning about the riddle of the Sphinx.
Get it wrong…and you were dead.
1:01 P.M.
AS GRAY’S flippers vanished into the tunnel, Rachel held her breath.
It was foolhardy madness. What if he got stuck? What if a section of the tunnel collapsed? One of the most dangerous forms of scuba diving was cave diving. Only those with a death wish enjoyed that sport.
And they had air tanks.
She clutched the edge of the rockface with her gloved fingers. Uncle Vigor shifted to her side. He placed his hand over hers, urging confidence.
Kat crouched by the opening. The woman’s flashlight pierced the dark tunnel. “I can’t see him.”
Rachel’s grip on the rock tightened.
Her uncle felt her flinch. “He knows what he’s doing. He knows his limits.”
Does he?
Rachel had recognized the edge of wildness about him in the last few hours. It both thrilled her and scared her. She had spent enough time with him. Gray did not think like other people. He operated at the fringes of common sense, trusting his quick thinking and reflexes to pull him out of tight scrapes. But the sharpest mind and fastest reflexes would not help you if a wall of rock dropped on top of your head.