"Hush up a minute," Hatch went on. "We also know that Macallan switched to a code containing all numbers."
"So?"
"So Macallan wasn't only a visionary, he was also a pragmatist. You've been approaching this second code as just a technical problem. But what if there's more to it than that? Could there be some pressing reason why Macallan used only numbers in the new code?"
There was a sudden silence in the hut as the cryptologist and the historian fell into thought.
"No," Wopner said after a moment.
"Yes!" St. John cried, snapping his fingers. "He used numbers to conceal his code tables!"
"What are you talking about?" Wopner grumbled.
"Look, Macallan was ahead of his time. He knew that polyalphabetics were the strongest codes around. But to use them, he needed several cipher alphabets, not just one. But he couldn't leave a lot of alphabet tables lying around where they might be discovered. So he used numbers! He was an architect and an engineer. He was supposed to have lots of numbers around. Mathematical tables, blueprints, hydraulic equations—any one of those could have done double duty, concealing a code table, and nobody would have been the wiser!"
St. John's voice had a clear, excited ring to it, and there was an eager flush on his face Hatch hadn't seen before. Wopner noticed it, too. He sat forward, the forgotten ice-cream sandwich melting into a brown-and-white pool on his desk.
"You might have something there, Chris old boy," he muttered. "I'm not saying you do, but you might." He pulled the keyboard toward him. "Tell you what. I'll reprogram the Cerberus computer to try a chosen-plaintext attack on the code. Now you boys let me be, okay? I'm busy."
Hatch accompanied St. John out of the hut and into the drizzle that cloaked Base Camp. It was one of those New England days when the moisture seemed to congeal out of the air itself.
"I should thank you," the historian said, pulling the sou'wester tighter around his plump face. "That was a good idea you had, you know. Besides, he'd never have listened to me. I was thinking about bringing the Captain into it."
"I don't know if I did anything, but you're welcome." Hatch paused. "Didn't you say that Isobel was looking for me?"
St. John nodded. "She said to say we've got a patient for you at the far end of the island."
Hatch started. "Patient? Why didn't you tell me first thing?"
"It's not urgent," said St. John with a knowing smile. "No, I wouldn't call it urgent, at all."
Chapter 25
As they mounted the rise of land, Hatch glanced southward. The cofferdam had been completed, and Streeter's crew was now working on the massive pumps arrayed along the western shore, tuning them up after their recent ordeal and preparing them for use again the next day. Orthanc stood gray and indistinct, the illumination from the observation tower casting a greenish neon glow into the surrounding mists. Hatch could see the faint shadow of someone moving about inside.
They topped the crown of the island and descended toward the east, following a muddy path that wound its way through an especially dense area of old shafts. The excavation site itself was spread across a flat meadow lying behind a sharp bluff on the eastern shore. A portable storage shed was standing on a platform of concrete blocks at the far end of the meadow. In front of it, the heavy grass had been trampled flat, and a great checkerboard grid had been marked out in white string across an acre of ground. Several large tarps lay in a disorganized heap. Here and there, Hatch could see that some of the meter-square grids had already been opened, exposing rich, iron-stained earth that contrasted sharply with the wet grass. Bonterre and several diggers were crowded together on an earthen balk beside one of the squares, their slicker-clad backs glistening, while another excavator was cutting out the sod in an adjacent square. A few large orange markers had been posted beyond the gridsite. It's a perfect spot for a pirate encampment, Hatch thought. Hidden from both the sea and the mainland.
A hundred yards from the site, the ATV had been parked at a crazy angle on the rough ground, a large gray box trailer in tow. Several large pieces of equipment on three-wheeled carts were lined up behind. Rankin was kneeling beside one, preparing to winch it back into the trailer.
"Where'd these toys come from?" Hatch asked, nodding at the equipment.
Rankin grinned. "The Cerberus, man, where else? Tomographic detectors."
"Come again?"
The grin widened. "You know. Ground-penetrating sensors." He began pointing to the various carts. "You got your ground-penetrating radar. Good resolution of bodies and, say, mines up to a dozen feet or so, depending on the wavelength. Next to it is an infrared reflector, good in sand but with relatively low saturation. And there at the end is—"
"Okay, okay, I get the idea," Hatch laughed. "All for non-metallic stuff, right?"
"You got it. Never thought I'd get a chance to use any of it on this gig. As it was, Isobel nearly had all the fun to herself." Rankin pointed at the orange markers. "You can see, I found a few scraps here and there, but she'd already struck the mother lode."
Hatch waved good-bye and trotted ahead to catch St. John. As they walked down to the site, Bonterre detached herself from the group and came over, slipping a hand pick into her belt and wiping her muddy hands on her rear. Her hair was tied back and her face and tawny arms were again smeared with dirt.
"I found Dr. Hatch," said St. John unnecessarily, a sheepish grin on his face.
"Thank you, Christophe."
Hatch wondered at the sheepish grin. Surely St. John hadn't become the latest victim of Bonterre's charms? But nothing else, he realized, could possibly have pried the man away from his books to grub about in the mud and rain.
"Come," she said, grabbing Hatch's hand and pulling him toward the edge of the pit. "Move aside," she barked amiably at the workers, "the doctor is here. Clear up your loose."
"What's this?" Hatch asked in amazement, gazing down at a dirty brown skull rearing out of the dirt, along with what looked like two feet and a jumble of other ancient bones.
"Pirate grave," she said, triumphantly. "Jump in. But do not step on anything."
"So this is the patient." Hatch climbed down into the excavated square. He examined the skull for a moment with interest, then turned his attention to the other bones. "Or should I say, patients."
"Pardon?"
Hatch looked up. "Unless this pirate had two right feet, you've got two skeletons here."
"Two? That is vachement bien!" cried Bonterre, clapping her hands.
"Were they murdered?" Hatch asked.
"Monsieur le docteur, that is your department."
Hatch knelt and examined the bones more closely. A brass buckle lay on a nearby pelvis, and several brass buttons were scattered across what remained of a rib cage, along with an unraveling string of gold piping. He tapped the skull slightly, careful not to prize it from the surrounding matrix. It was turned to one side, mouth gaping open. There were no obvious pathologies: no musket ball holes, broken bones, cutlass marks, or other signs of violence. He couldn't really be sure what killed the pirate until the excavation was complete and the bones had been removed. On the other hand, it was clear that the original body had been buried in haste, even thrown into the grave: the arms lay askew, the head was turned and the legs bent. He wondered for a moment if the rest of the second skeleton lay beneath. Then his eyes were suddenly arrested by a golden gleam near one of the feet.
"What's this?" he asked. A compact mass of gold coins and a large, carved gemstone lay embedded in the earth near the lower tibia. Only a little of the soil had been brushed away, keeping the coins in situ.