Douglas Preston - Riptide

He struck a few keys. "Let's see if we can clear away everything but the original works." Most of the colored lines disappeared, leaving only red. Now the diagram made more sense to Hatch: He could clearly see the big central shaft plunging into the earth. At the hundred-foot level, a tunnel led to a large room: the vault where Wopner was killed. Deeper, near the bottom of the Pit, six smaller tunnels angled away like the fingers of a hand; directly above, a large tunnel climbed sharply to the surface. There was another narrow tunnel angling away from the bottom, plus a small array of side workings.

St. John pointed to the lower set. "Those are the six flood tunnels?"

"Six?"

"Yes. The five we found, plus one devilish tunnel that didn't expel any dye during the test. Magnusen said something about a clever hydrological backflow system. I didn't understand half of it, to be honest." He frowned. "Hmm. That tunnel right above with the gentle slope is the Boston Shaft, which was built much later. It shouldn't be displayed as part of the original works." A few more keystrokes, and the offending tunnel disappeared from the screen.

St. John glanced quickly at Hatch, then looked back at the screen again. "Now, this tunnel, the one that angles toward the shore—" He swallowed. "It isn't part of the central Pit, and it won't be fully explored for some time yet. At first, I thought it was the original back door to the Pit. But it seems to come to a waterproofed dead end about halfway to the shore. Perhaps it's somehow linked to the booby trap that your brother..." His voice trailed off awkwardly.

"I understand," Hatch managed to say, his own voice sounding dry and unnaturally thin to his ears. He took a deep breath. "They're making every effort to explore it, correct?"

"Of course." St. John stared at the computer screen. "You know, until three days ago I admired Macallan enormously. Now I feel very differently. His design was brilliant, and I can't blame him for wanting his revenge on the pirate who abducted him. But he knew perfectly well this Pit could just as easily kill the innocent as the guilty."

He began rotating the structure again. "Of course, the historian in me would say Macallan had every reason to believe Ockham would live long enough to come back and spring the trap himself. But the Pit was designed to live on and on, guarding the treasure long after Ockham died trying to get it out."

He punched another key, and the diagram lit up with a forest of green lines. "Here you can see all the bracing and cribbing in the main Pit. Four hundred thousand board feet of heart-of-oak. Enough to build two frigates. The structure was engineered to last hundreds of years. Why do you suppose Macallan had to build his engine of death so strong? Now, if you rotate it this way—" He poked another button, then another and another. "Damn," he muttered as the structure began to whirl quickly around the screen.

"Hey, you're going to burn out the video RAM if you twirl that thing any faster!" Rankin, the geologist, stood in the doorway, his bearlike form blotting out the hazy morning light. His blond beard was parted in a lopsided smile.

"Step away from that before you break it," he joked, closing the door and coming toward the screen. Taking St. John's seat, he tapped a couple of keys and the image obediently stopped spinning, standing still on the screen as if at attention. "Anything yet?" he asked the historian.

St. John shook his head. "It's hard to see any obvious patterns. I can see parallels here and there to some of Macallan's hydraulic structures, but that's about it."

"Let's turn it around the Z-axis at five revolutions per minute. See if it inspires us." Rankin hit a few keys and the structure on the screen began rotating again. He settled back in his chair, threw his arms behind his head, and glanced at Hatch. "It's pretty amazing, man. Seems your old architect may have had some help with his digging, in a manner of speaking."

"What kind of help, exactly?"

Rankin winked. "From Mother Nature. The latest tomographic readings show that much of the original Pit was already in place when the pirates arrived. In natural form, I mean. A huge vertical crack in the bedrock. That might even have been the reason Ockham chose this island."

"I'm not sure I understand."

"There's a huge amount of faulting and displacement in the metamorphic rock underlying the island."

"Now I'm sure I don't understand," Hatch said.

"I'm talking about an intersection of fault planes right under the island. Planes that got pulled apart somehow."

"So there were underground cavities all along?"

Rankin nodded. "Lots. Open cracks and fractures running every which way. Our friend Macallan merely widened and added as needed. But the question I'm still struggling with is, why are they here, under this island only? Normally, you'd see that kind of displacement on a wider scale. But here it seems restricted to Ragged Island."

Their talk was interrupted as Neidelman stepped into the hut, He looked at each of them in turn, a smile flicking across his face, then vanishing again. "Well, Malin, did Sandra give you the permission chit?"

"She did, thanks," Hatch replied.

Neidelman turned toward Rankin. "Don't stop on my account."

"I was just helping St. John here with the 3-D model," Rankin said.

Hatch looked from one to the other. The easygoing geologist suddenly seemed formal, on edge. Has something happened between these two? he wondered. Then he realized it was something in the way Neidelman was looking at them. He, too, felt an almost irresistible urge to stammer out excuses, explanations for what they were doing.

"I see," Neidelman said. "In that case, I have good news for you. The final set of measurements has been entered into the network."

"Great," Rankin said, and tapped a few more keys. "Got it. I'm integrating now."

As Hatch watched the screen, he saw small line segments being added to the diagram with blinding speed. In a second or two, the download was complete. The image looked much the same, though even more densely woven than before.

St. John, looking over the geologist's shoulder, sighed deeply. Rankin hit a few keys and the model began spinning slowly on its vertical axis once again.

"Take out all but the very earliest structures," St. John said.

Rankin tapped a few keys and countless tiny lines disappeared from the image on the screen. Now, Hatch could see just a depiction of the central Pit itself.

"So the water traps were added toward the end," Neidelman said. "Nothing we didn't already know."

"See any design elements common to Macallan's other structures?" Rankin asked. "Or anything that might be a trap?"

St. John shook his head. "Remove everything but the wooden beams, please." Some more tapping and a strangely skeletal image appeared against the blackness of the screen.

The historian sucked in his breath with a sudden hiss.

"What is it?" Neidelman asked quickly.

There was a pause. Then St. John shook his head. "I don't know." He pointed to two places on the screen where several lines intersected. "There's something familiar about those joints, but I'm not sure what."

They stood a moment, a silent semicircle, gazing at the screen.

"Perhaps this is a pointless exercise," St. John went on. "I mean, what kind of parallels can we really hope to find to Macallan's other structures? What buildings are ten feet across and a hundred forty plus feet tall?"

"The leaning tower of Pisa?" Hatch suggested.

"Just a minute!" St. John interrupted sharply. He peered more closely at the screen. "Look at the symmetrical lines on the left, there, and there. And look at those curved areas, one below the other. If I didn't know better, I'd say they were transverse arches." He turned toward Neidelman. "Did you know the Pit narrowed at the halfway point?"