Riptide

by Douglas Preston

  "I owe a lot of it to you," Hatch said. He remembered afternoons in the professor's huge Victorian house in the back meadows—poring over his collections of rocks, beetles, and butterflies—in those last years before leaving Stormhaven.

  "Nonsense. I still have your bird nest collection, by the way. Never knew where to send it after you left."

  Hatch felt a twinge of guilt. It had never occurred to him that the august professor would have wanted to hear from him. "I'm surprised you didn't throw that junk away."

  "Actually, it was a remarkably good collection." He shifted his hand to Hatch's arm and held it in a bony clasp. "See me out the fort and across the meadow, would you? I'm a little shaky on my wheels these days."

  "I would have gotten in touch . . ." Hatch's voice trailed away.

  "Not a word, not even a forwarding address," the professor said acidly. "Then I read about you in the Globe last year."

  Hatch turned away, feeling shame burning his face.

  The professor gave a gruff snort. "No matter. According to the actuarial tables I should be dead. I'll be eighty-nine next Thursday, and damn you if you don't bring me a present."

  They emerged into the sunlight of the meadow. Voices raised in laughter drifted toward them on the breeze.

  "You must have heard why I came back," Hatch said tentatively.

  "Who hasn't?" was the tart reply. The professor offered nothing further, and they walked on in silence for a moment.

  "So?" Hatch said at last.

  The old man looked at him inquiringly.

  "So drop the other shoe," Hatch continued. "What do you think of this treasure hunt?"

  The professor walked on for a minute, then stopped and turned toward Malin, lowering his arm as he did so. "Remember, you asked," he said.

  Hatch nodded.

  "I think you're a goddamned fool."

  There was a moment of stunned surprise. He'd been prepared for Clay, but not for this. "What makes you say that?"

  "You, of all the people on this earth, should know better. Whatever's down there, you won't get it out."

  "Look, Dr. Horn, we've got technology those old treasure hunters never even dreamed of. Hardbody sonar, proton magnetometers, a photo-reconnaissance satellite downlink. We've got twenty million dollars in funding, and we even have the private journal of the man who designed the Pit." Hatch's voice had risen. He suddenly realized that it was very important for him to have this man's good opinion.

  Dr. Horn shook his head. "Malin, for almost a century I've seen them come and go. Everyone had the latest equipment. Everyone had gobs of money. Everyone had some crucial piece of information, some brilliant insight. It was always going to be different. And they all ended up the same. Bankruptcy, misery, even death." He glanced at Hatch. "Have you found any treasure yet?"

  "Well, not yet," Hatch said. "There's been one small problem. We knew that the Pit must have an underground flood tunnel leading to the sea, that's why it's always filled with water. We used dye to locate the flood tunnel's exit on the sea floor. Only, it seems there's not one flood tunnel, but five, and—"

  "I see," Dr. Horn interrupted. "Just one small problem. I've heard that before, too. Maybe you'll solve your problem. Only then there will be another problem, and another, until you're all bankrupt. Or dead. Or both."

  "But this will be different," Hatch cried. "You can't tell me it's impossible to raise the treasure. What man created, man can defeat."

  The professor suddenly gripped Hatch's arm again. He had alarmingly strong hands, corded like ancient tree roots, sinewy and dry. "I knew your grandfather, Malin. He was a lot like you: young, smart as hell, promising career ahead of him, terrific enthusiasm for life. What you just said is exactly what he said to me, word for word, fifty years ago." He lowered his voice to a fierce whisper. "Look at the legacy he left your family. You asked my opinion. So here it is in a nutshell. Go back to Boston before history repeats itself."

  He turned brusquely and hobbled off, his cane flicking irritably through the grass, until he had disappeared over the brow of the hill.

  Chapter 18

  The next morning, a little bleary-eyed from the beer of the previous day, Hatch closeted himself in the medical hut, laying out instruments and taking inventory. There had been a number of injuries over the last several days, but nothing more serious than a few scrapes and a cracked rib. As he moved through his shelves, checking against a printed master list, he could hear the monotonous hiss of surf from the nearby reefs. The sun struggled wanly through the metal-sided window, attenuated by the omnipresent curtain of mist.

  Finishing the inventory, Hatch hung his clipboard beside the shelves and glanced out the window. He could see the tall, slope-shouldered form of Christopher St. John, walking gingerly over the rough ground of Base Camp. The Englishman dodged a heavy cable and a length of PVC pipe, then ducked into Wopner's quarters, his unruly gray hair barely clearing the door frame. Hatch stood for a moment, then picked up the two black binders and exited the medical office, following the historian. Maybe there was some progress to report on the code.

  Wopner's Base Camp office was, if anything, even more messy than his stateroom on the Cerberus. Small to begin with, banks of monitoring and servo control equipment made it claustrophobic. Wopner occupied the office's lone chair, crammed into a far corner by the relay racks that surrounded him. Cold air was blasting from two ducts overhead, and a massive air conditioner grumbled on the far side of the wall.

  Despite the air-conditioning, the room was stuffy with hot electronics, and as Hatch walked in St. John was looking for a place to hang his jacket. His search unsuccessful, he laid it carefully on a nearby console.

  "Jeez," said Wopner, "you lay your hairy old tweed there and it's gonna short-circuit the whole works."

  Frowning, St. John picked it up again. "Kerry, do you have a minute?" he said. "We really need to discuss this problem with the code."

  "Do I look like I have a minute?" came the response. Wopner leaned away from his terminal with a glare. "I've just now finished an all-island diagnostic. The whole ball of wax, right down to the microcode. Took an hour, even at maximum bandwidth. Everything checks out: pumps, compressors, servos, you name it. No problems or discrepancies of any kind."

  "That's great," Hatch broke in.

  Wopner looked at him incredulously. "Grow a brain, willya? Great? It's frigging terrible!"

  "I don't understand."

  "We had a system crash, remember? The goddamn pumps went south on us. Afterward, I compared the island computer system with Scylla over on the Cerberus, and guess what? The ROM chips on Charbydis, here, had been altered. Altered!" He angrily smacked one of the CPUs upside its cabinet.

  "And?"

  "And now I run the diagnostics again, and everything's fine. Not only that, but the entire grid shows no deviations of any kind." Wopner leaned forward. "No deviations. Don't you get it? That's A physical and computational impossibility."

  St. John was glancing at the equipment around him, hands tucked behind his back. "Ghost in the machine, Kerry?" he ventured.

  Wopner ignored this.

  "I don't know much about computers," St. John continued, his plummy accent filling the air, "but I do know one term: GIGO. Garbage in, garbage out."

  "Bite me. It's not the programming."

  "Ah. I see. Couldn't possibly be human error. As I recall, all it took was one incorrect FORTRAN equation to send Mariner 1 off on some outer space scavenger hunt, never to be heard from again."

  "The point is, things are working now," Hatch said. "So why not move on?"

  "Sure, and have it happen again. I want to know why all this shit failed at once."

  "You can't do anything about it now," St. John said. "Meanwhile, we're falling behind schedule on the cryptanalysis. Nothing's worked. I've done some more research, and I think we've been far too quick to dismiss—"

  "Shit on a stick!" Wopner snapped, wheeling toward him. "You're not going to start mum
bling about polyalphabetics again, are you, old thing? Look, I'm going to modify the algorithm of my brute-force attack, give it fifty percent system priority, really get things moving. Why don't you retire to your library? Come back at the end of the day with some useful ideas."

  St. John looked briefly at Wopner. Then he shrugged into his tweed and ducked back out into the gauzy morning light. Hatch followed him to his own office.

  "Thanks," Hatch said, passing the two folders to St. John.

  "He's right, you know," the historian said, taking a seat at his tidy desk and wearily pulling the old typewriter toward him. "It's just that I've tried everything else. I've based my attacks on all the encryption methods known during Macallan's time. I've approached it as an arithmetic problem, as an astronomic or astro-logic system, as a foreign language code. Nothing."

  "What are polyalphabetics?" Hatch asked.

  St. John sighed. "A polyalphabetic cipher. It's quite simple, really. You see, most codes in Macallan's day were simple, monophonic substitutions. You had the regular alphabet, then you had a cipher alphabet, all higgledy-piggledy. To encode something, you simply looked up which cipher letter matched the next regular letter in your document. Maybe the code for s was y, and the code for e was z. So, when you coded the word 'see,' you'd get 'yzz.' That's how the cryptograms in your local newspaper work."

  "Seems clear enough."

  "Yes. But it's not a very secure system. So what if you had several different cipher alphabets to work with? Let's say instead of just one, you had ten. And, as you encrypted your document letter by letter, you'd move through all ten cipher alphabets, and then start over again with the first. That's a polyalphabetic cipher. Now, 'see' wouldn't just be 'yzz.' Each letter would be coded from a different cipher table."

  "Sounds difficult to crack."

  "Yes, they are very difficult. But Kerry's point is that polyalphabetics weren't used in Macallan's day. Oh, people knew about them. But they were considered too time-consuming, too prone to error." St. John sighed again. "But in this case, the biggest problem is one of concealment. If Macallan used a polyalphabetic cipher, how could he have safely hidden all the code alphabet tables he would have needed? Just one chance look at those by Red Ned Ockham would give the whole game away. And as bright as he was, he couldn't have memorized them."

  "If you think there's the chance it's a polyalphabetic code, why don't you try cracking it on your own?"

  The corners of St. John's lips lifted in what might have been a smile. "If I had two months, I'd be happy to give it a try. But I don't. Besides, I have no idea how long a key he was using, if any, or how liberally he'd strewn his nulls."

  "Nulls?"

  "Nihil importantes. Letters that don't stand for anything, but are tossed in to confuse the codebreaker."

  A boat horn sounded outside, deep and mysterious, and Hatch checked his watch. "It's ten," he said. "I'd better go. They'll be sealing the flood tunnels and draining the Water Pit in a few minutes. Good luck with Kerry."

  Chapter 19

  Leaving Base Camp, Hatch began jogging up the path toward Orthanc, eager to see the new structure that had materialized over the Water Pit in just forty-eight hours. Even before he reached the crest of the island, he could make out the glassed-in observation tower, a narrow deck running around its outer edge. As he drew closer, he could see the massive supports that suspended the derrick almost forty feet above the sandy ground. Winches and cables dangled from the underside of the tower, reaching down into the darkness of the Pit. My God, Hatch thought. They must be able to see this thing from the mainland.

  With this, his thoughts drifted back to the lobster festival and to what Clay and his old teacher had said. He knew that Professor Horn would keep his opinions to himself. Clay, though, was another matter. So far, public sentiment toward Thalassa seemed overwhelmingly favorable; he'd have to be careful to keep it that way. Even before the festival had come to a close, he'd spoken to Neidelman about giving Donny Truitt a job. The Captain had promptly added him to the excavation crew that would start digging at the bottom of the Water Pit as soon as it was drained.

  Hatch approached the derrick and climbed the external ladder. The view from the observation deck was magnificent. The ever-present mist was breaking into tatters under the hot summer sun, and he could just make out the dark purple stripe of the mainland. The sun glinted off the ocean, turning it the color of beaten metal, and the surf broke over the windward reefs, surrounding them with spume and a line of drifting wrack. A phrase from Rupert Brooke surfaced unbidden in his mind:

  The little dulling edge of foam

  That browns and dwindles as the wave goes home.

  He raised his head at the sound of voices. On the far side of the observation deck he could see Isobel Bonterre, her wetsuit shining damply in the sun. She was leaning over the railing, twisting the excess water out of her hair and talking animatedly to Neidelman.

  As Hatch strolled over, she turned to him with a grin. "Well, well! The man who saved my life!"

  "How's your wound?" Hatch replied.

  "De rien, monsieur le docteur. I was out diving this morning at six, no doubt while you were still snoring the loud snores. And you will not believe what I have discovered!"

  Hatch glanced at Neidelman, who was nodding and puffing on his pipe, clearly pleased.

  "That stone foundation I found on the seabed the other day?" she continued. "It runs along the inside wall of the reefs, all around the southern end of the island. I traced the remains this morning. There is only one explanation for it: the foundation to an ancient cofferdam."

  "An ancient cofferdam? Built around the end of the island? But why?" Even as Hatch asked the question, he realized the answer. "Jesus," he exhaled.

  Bonterre grinned. "The pirates built a semicircular dam all along the southern reefs. They sunk wooden pilings, arcing out from the shore into the shallow water, then coming back to land again, like a stockade fence in the sea. I found tracings of pitch and oakum, which they probably used to make the pilings watertight. Then they pumped out the seawater, exposed the sea floor around the beach, and excavated the five flood tunnels.

  When they were done, they simply destroyed the cofferdam and let the water back in. Et voila, the traps were set!"

  "Yes," Neidelman added. "Almost obvious, when you think of it. How else could they build underwater flood tunnels without the benefit of scuba gear? Macallan was an engineer as well as an architect. He advised on the construction of Old Battersea Bridge, so he knew about shallow-water construction. He undoubtedly planned all of this, down to the last detail."

  "A cofferdam around the entire end of the island?" Hatch said. "Sounds like a huge task."

  "Huge, yes. But remember, he had over a thousand enthusiastic laborers to do it. And they had enormous chain pumps from the bilges of their ships." There was another blast from a boat horn, and Neidelman checked his watch. "Fifteen minutes until we blow the explosives and seal those five flood tunnels. The mist is clearing nicely; we should have a fine view. Come on inside."

  The Captain ushered them inside Orthanc. Beneath the windows that lined the walls of the tower, Hatch could see banks of equipment and horizontally mounted monitors. Magnusen and Rankin, the geologist, stood at stations in opposite corners of the tower, while a couple of technicians Hatch didn't recognize were busy wiring and testing components. Against one wall, a series of screens showed closed-circuit video feeds from around the island: the Command Center, the mouth of the Pit, the interior of Orthanc itself.

  The most remarkable feature of the tower was a massive glass plate that occupied the center of the floor. Hatch stepped forward and gazed down into the maw of the Water Pit.

  "Watch this," Neidelman said, flicking a switch on a nearby console.

  A powerful mercury arc lamp snapped on, its beam stabbing down into the darkness. Below, the Pit was drowned in seawater. Bits of seaweed floated in the water and brine shrimp, attracted by the light, jerked and pl
ayed just below the surface. A few feet into the murky water, he could make out stumps of old timbers, heavy with barnacles, their ragged lengths disappearing into the depths. The fat, metal-jointed pump hose ran along the ground and over the side of the Pit, joining half a dozen other, narrower cables and feeder lines.

  "The throat of the beast," Neidelman said with grim satisfaction. He swept his hand over the consoles ranged beneath the windows. "We've equipped the tower with the latest remote-sensing equipment, including L-band and X-band synthetic-aperture downward-pointing radar. All with dedicated links to the Base Camp computer."

  He checked his watch again. "Dr. Magnusen, is the comm station in order?"

  "Yes, Captain," the engineer said, brushing her short hair back. "All five marker buoys are transmitting clearly, ready for your arming signal."

  "Is Wopner in Island One?"

  "I beeped him about five minutes ago. He should be there shortly, if he isn't already."

  Neidelman strode toward a bank of controls and snapped the radio to life. "Naiad and Grampus, this is Orthanc. Do you read?"

  The boats acknowledged.

  "Take your stations. We blow the charges in ten minutes."

  Hatch moved to the window. The mist had retreated to a distant haze, and he could see the two launches power away from the pier and take up positions offshore. Ringing the inside of the reef, along the southern end of the island, he could make out the five electronic buoys that marked the flood tunnel exits. Each flood tunnel, he knew, had now been mined with several pounds of Semtex. The buoy antennas winked in the light, ready to receive the detonation signals.

  "Island One, report," Neidelman spoke into the radio.