After comparing, it was decided to go topside in twenty minutes. They'd take a half-hour break, then back into the water.

As he swam, he went back to his original pondering. He kept sensing they had missed something critical. What if the Dragon Court had taken some object from the cave, a second clue? He kicked harder. He had to let that fear go. He had to proceed as though he had the same intel as the Court, an equal playing field.

The silence of the deep pressed on him. "This just doesn't seem right," he mumbled.

The radio transmitted his voice.

"Did you find something?" Kat asked. Her shadowy form drifted closer.

"No. That's just it. The longer I'm down here, the more I'm convinced we're doing this wrong."

"I'm sorry," Rachel said from out of nowhere, sounding hopeless. "I probably put too much emphasis-"

"No." Gray remembered her worry topside. He kicked himself for rekindling it. "Rachel, I think you've targeted the correct place to search. The problem is my my plan. This whole searching quadrant by quadrant. It just doesn't feel right." plan. This whole searching quadrant by quadrant. It just doesn't feel right."

"What do you mean, Commander?" Kat asked. "It may take some time, but we'll get the area covered."

That was just it. Kat had clarified it for him. He wasn't one for systematic, dogged methodology. While some problems were best solved that way, this mystery wasn't one of them.

"We've missed a clue," he said. "I know it. We recognized the map in the tomb, realized it pointed to Alexander's tomb, then flew here. We searched records, books, and files, trying to solve a riddle that has baffled historians for more than a millennium. Who are we to solve it in one day?"

"So what do you want us to do?" Kat asked.

Gray settled to a stop. "We go back to square one. We've based our search on historical records available to anyone. The only advantage we have over all the treasure hunters of the past centuries is what was discovered under Saint Peter's tomb. We missed a clue down there."

Or one was stolen, Gray thought. But he did not speak this worry aloud. Gray thought. But he did not speak this worry aloud.

"Maybe we didn't miss a clue at the tomb," Vigor said. "Maybe we didn't look deep enough. Remember the catacombs. The riddles were multilayered, multifathomed. Could there be another layer to this riddle?"

Silence answered him...until an unexpected voice solved it all.

"That G.o.dd.a.m.n fiery star," Monk swore. "It wasn't just pointing down at the city of Alexandria...it was pointing down at the stone slab."

Gray felt the ring of truth in Monk's words. They had been so focused on the inscribed map, the fiery star, the implication of it all, but they had ignored the unusual medium of the artist.

"Hemat.i.te," Kat said.

"What do you know about it?" Gray asked, trusting her background in geology.

"It's an iron oxide. Large deposits have been found throughout Europe. It is mostly iron, but sometimes it contains a fair amount of iridium and t.i.tanium."

"Iridium?" Rachel said. "Isn't that one of the elements in the amalgam? In the Magi bones?"

"Yes," Kat said, voice suddenly sounding strained over the radio. "But I don't think that's the significant part."

"What?" Gray asked.

"I'm sorry, Commander. I should have thought of it. The iron in hemat.i.te is often weakly magnetic magnetic, not as strongly as magnet.i.te, but it's sometimes used as a lodestone."

Gray realized the implication. Magnetism had also opened the first tomb. "So the star wasn't just pointing to Alexandria, it was pointing to a magnetized stone, something we're supposed to find."

"And what did the ancient world do with lodestones?" Vigor asked, excitement growing in his voice.

Gray knew the answer. "They made compa.s.ses!" He fed air into his BC vest and rose toward the surface. "Everyone topside!"

11:10 A A.M.

IN A matter of minutes, they were shedding tanks, vests, and weight belts. Rachel climbed into the pilot's seat, glad to sit down. She pressed the b.u.t.ton to raise the anchor. It chugged upward. matter of minutes, they were shedding tanks, vests, and weight belts. Rachel climbed into the pilot's seat, glad to sit down. She pressed the b.u.t.ton to raise the anchor. It chugged upward.

"Go slow," Gray said. He had taken up a post at her shoulder.

"I second that," Monk said.

"I'll watch the compa.s.s," Gray continued. "You keep us on a snail-paced circuit around the fort. Any twitch on the compa.s.s needle and we drop anchor and search below."

Rachel nodded. She prayed that whatever magnetized stone lay down there, it was strong enough for their shipboard compa.s.s to detect.

With the anchor retracted, she eased the throttle to the barest chop of her propellers. Motion forward was barely detectable.

"Perfect," Gray whispered.

Onward they glided. The sun slowly rose into the sky overhead. They pulled up the boat's canopy to shade the group as the day's heat climbed. Monk lay sprawled on the portside bench, slightly snoring. No one spoke.

Worry grew in Rachel with each slow turn of the boat's propeller.

"What if the stone isn't out here?" she whispered to Gray, who kept a vigil on the compa.s.s. "What if it's inside the fort?"

"Then we'll search there next," Gray said, squinting toward the stone citadel. "But I think you're right about a secret entrance. The hemat.i.te slab sat over a secret tunnel to the cavern that led down to a river channel. Water. Perhaps that's another layer of the riddle."

Kat heard them, a book open on her lap. "Or we're reading too much into it," she said. "Trying to force what we want to match the riddle."

Up in the bow end, Vigor ma.s.saged a sore calf muscle from the swim. "I think the ultimate question of where the stone might lie-on land or in the water-depends on when when the alchemists hid the clue. We estimated the clues were hidden sometime around the thirteenth century, maybe a little before or a little after, but that's the critical era of conflict between Gnosticism and orthodoxy. So, did the alchemists hide their next clue before or after the Pharos Lighthouse collapsed in 1303?" the alchemists hid the clue. We estimated the clues were hidden sometime around the thirteenth century, maybe a little before or a little after, but that's the critical era of conflict between Gnosticism and orthodoxy. So, did the alchemists hide their next clue before or after the Pharos Lighthouse collapsed in 1303?"

No one had an answer.

But a few minutes later, the compa.s.s needle gave a shaky twitch.

"Hold it!" Gray hissed.

The needle steadied again. Kat and Vigor glanced to them.

Gray placed a hand on Rachel's shoulder. "Go back."

Rachel tweaked the throttle into neutral. Forward momentum stopped. She let the waves bob them backward.

The needle pitched again, swinging a full quarter turn.

"Drop anchor," Gray ordered.

She pressed the release, hardly breathing.

"Something's down there," Gray said.

Everyone began to move at once, grabbing for fresh tanks.

Monk woke with a start, sitting up. "What?" he asked blearily.

"Looks like you're going on guard duty again," Gray said. "Unless you want to take a dip?"

Monk scowled his answer.

Once the boat was secure and the orange flag raised, the same four divers fell back into the water.

Rachel bubbled out her buoyancy and sank under the waves.

Gray's voice reached her through the radio. "Watch your wrist compa.s.ses. Zero in on the anomaly."

Rachel studied her compa.s.s as she descended. The water was fairly shallow here. Less than ten meters. She reached the sandy bottom quickly. The others dropped around her, hovering like birds.

"Nothing's here," Kat said.

The seabed was a flat expanse of sand.

Rachel stared at her compa.s.s. She kicked a body length away, then back again. "The anomaly is right here."

Gray lowered to the bottom and swept his wrist over the floor. "She's right."

He reached to his other wrist and unsheathed his knife. With the blade in hand, he began stabbing into the soft sand. The blade sank to the hilt each time. Silt stirred up, clouding the view.

On his seventh stab, the knife plainly jarred, failing to penetrate more than a few centimeters.

"Got something," Gray said.

He sheathed the knife and began digging in the sand. The view grew quickly murky, and Rachel lost sight of him.

Then she heard him gasp.

Rachel moved closer. Gray swept back. The disturbed sand dispersed and settled.

Protruding from the sand was a dark bust of a man.

"I think that's magnet.i.te," Kat said, studying the stone of the sculpture. She swept her wrist compa.s.s over the bust. The needle twirled. "Lodestone."

Rachel edged closer, staring at the face. There was no mistaking the features. She had seen the same countenance a couple of times today.

Gray recognized it, too.

"It's another sphinx."

12:14 P P.M.

GRAY SPENT ten minutes clearing the shoulders and upper torso, reaching the lion's shape below. There was no doubt it was one of the sphinxes, like the others littered on the seabed. ten minutes clearing the shoulders and upper torso, reaching the lion's shape below. There was no doubt it was one of the sphinxes, like the others littered on the seabed.

"Hiding it among the others," Vigor said. "I guess that answers the question of when the alchemists hid their treasure here."

"After the lighthouse collapsed," Gray said. the lighthouse collapsed," Gray said.

"Exactly."

They hovered around the magnetic sphinx, waiting for the disturbed silt and sand to settle.

Vigor continued, "This ancient society of mages must have known the location of Alexander's tomb after Septimus Severus hid it in the third century. They left it undisturbed, letting it safeguard the most valuable scrolls from the lost library. Then perhaps the quake in 1303 not only brought down the lighthouse, but exposed the tomb. They took the opportunity to hide more down there, using the chaotic time after the earthquake to plant their next clue, bury it, and allow the centuries to cover it up again."

"And if you're right," Gray said, "that pinpoints the date when these clues were planted. Remember, we'd already estimated that the clues were laid around the thirteenth century. We were off by only a few years. It was 1303. The first decade of the fourteenth century."

"Hmm..." Vigor drifted closer to the statue.

"What?"

"It makes me wonder. In that same decade, the true papacy was chased out of Rome and exiled in France. The antipopes ruled Rome for the next century."

"So?"

"Similarly, the Magi bones were moved from Italy to Germany in 1162, another time when the true pope was chased out of Rome and an antipope sat on the papal seat."

Gray followed this train of thought. "So these alchemists hid their stuff whenever the papacy was in jeopardy."

"So it would seem. This would suggest that this society of mages had ties to the papacy. Perhaps the alchemists did indeed join the Gnostic Christians of those turbulent times, Christians open to the quest for arcane knowledge, the Thomas Thomas Christians." Christians."

"And this secret society merged with the orthodox church?"

Vigor nodded in the murky water. "When the overall church came under threat, so did the secret church. So they sought safeguards. First moving the bones to safety in Germany during the twelfth century. Then during the embattled years of the exile, they hid the true heart of their knowledge."

"Even if this is true, how does this help us find Alexander's tomb?" Kat asked.

"Just as the clues that led to Saint Peter's tomb were buried in the stories of Catholicism, the clues here might be tied to the mythologies of Alexander. Greek mythologies." Vigor ran a gloved finger down the face of the statue. "Why else mark the gateway with a sphinx?"

"The riddle masters of the Greeks," Gray mumbled.

"And the monsters killed you outright if you didn't answer them correctly," Vigor reminded them. "Perhaps choosing this symbol is a warning."

Gray studied the sphinx as the sand cleared, its expression enigmatic. "Then we'd better solve this riddle."

12:32 P P.M.

FINAL DESCENT INTO ALEXANDRIA.

THE GULFSTREAM IV private jet received clearance from the tower to land. Seichan listened to the chatter of the c.o.c.kpit crew through the open doorway. She sat in the seat nearest the door. Sunlight blazed through the window on her right. IV private jet received clearance from the tower to land. Seichan listened to the chatter of the c.o.c.kpit crew through the open doorway. She sat in the seat nearest the door. Sunlight blazed through the window on her right.