Testament

1

Marine archaeologist Jack Howard stared down into the abyss, hearing nothing but the hiss of his oxygen rebreather as he floated in the deep ocean swell. Somewhere down there, somewhere in the inky blackness below, lay a prize beyond the dreams of most deep-sea salvors, a king’s ransom in gold resting unclaimed in international waters. But at the moment, Jack was far less concerned about the gold than about the diver who had just preceded him. Costas had plummeted in his usual fashion, like a sack of lead, weighed down by the array of tools on his belt. As their rebreathers produced no bubbles, he had disappeared almost without a trace, barely leaving a quiver in the shot line that anchored them to the wreck. After more than twenty years of diving together, Jack had seen his friend disappear down more black holes than he cared to remember, but this time, more than fifty miles from shore in the forbidding waters of the South Atlantic, it had been particularly unnerving. They had the experience to confront virtually anything the oceans had to offer, but Jack knew that what sailors used to call divine providence would always have the final say. Not for the first time over the last few years, he shut his eyes and mouthed the words he always did before a perilous dive into the unknown: Lucky Jack.

He opened his eyes and checked the LED display inside his helmet. He remembered the last time he had watched Costas disappear into the abyss, in the Mediterranean five months earlier during their hunt for a pharaoh’s lost sarcophagus. Costas had been trapped inside a submersible that had lost its tether and was falling to the ocean floor, and Jack had made a split-second decision to freedive after it, a one-way ticket to oblivion had he failed to reach it in time. Then, there had been no time for reflection, no time for fear. But this time the few minutes he had spent on the surface after watching Costas go had been enough for his heart rate to increase, for his mouth to go dry. His computer had flashed up a yellow warning just as they were about to descend together, too late for him to signal Costas to abort. The diagnostic in his helmet display had shown the reappearance of a glitch in the first-stage rebreather manifold, something that Costas had tried to fix in the support vessel’s repair shop before the dive, a fraught few hours during which Jack had been locked in an argument with the captain about the need to keep the shot-line anchor out of the wreckage in order to avoid damaging the sunken hull even before they had begun to explore it.

All he could do now was wait for his computer to complete the diagnostic and hope that it could repair itself. Their communication system was down too, meaning he could no longer talk to Costas, a problem not with their own equipment but with the link to the ship’s control room. That and the lack of specialized tools in the repair shop had been just two of the small irritations since they had been winched down by helicopter with their equipment onto Deep Explorer the day before.

He rolled sideways, seeing the unfamiliar hull a few meters beyond the shot-line buoy. Instead of Seaquest, instead of the support divers from the International Maritime University and the submersible that would normally accompany a dive of this nature, they were operating from a commercial salvage vessel without any of the usual IMU safety backup. They were here because a landmark change in legislation had finally seen British merchant vessel wrecks of the Second World War designated as war graves. They were also here because a researcher for the salvage company had found a secret cargo manifest showing that the ship below them, the SS Clan Macpherson, sunk by a U-boat in 1943, had been carrying a consignment of two tons of gold. Without that gold, the salvors would have had no interest in the wreck. With it, they were prepared to destroy the wreck to get at the cargo.

This had been the first case since the legislation had been passed, and Jack had agreed to spearhead the UN monitoring program, knowing that his clout as archaeological director of IMU would ensure that the wreck would be front-page news if things went awry. The salvage company knew that too, and apart from this morning’s spat over the anchor chain, relations had been businesslike. They may have thought they were on an easy ride, with two of the world’s foremost maritime archaeologists here to verify the wreck and provide guidelines for the salvage, a token requirement that they could make a great show of following while they went ahead and ripped the wreck apart to get at the gold, something the world’s press were hardly going to see more than a hundred meters below the sea. Jack was determined to do anything he could to prevent that from happening.

He heard the roar of an outboard engine, and moments later saw a Zodiac swing out from the stern of the vessel with several crew on board and head toward him. He motioned for them to come between him and the ship, a safer option in the mounting swell than being trapped in a narrow space between the two vessels. The crewman at the tiller throttled down and put the engine in neutral as he came alongside. Jack grabbed the rope around the edge of the inflatable and hung on as the project logistics director, a former oil-rig foreman named Macinnes, leaned over. “What’s the problem?” he shouted.

Jack was wearing a full-face mask as part of his IMU e-suit, an all-environment drysuit with integrated buoyancy system that Costas had perfected over the years. He was not willing to raise the mask while he was in the water, but he clicked open a one-way valve beside his mouthpiece that would allow him to be heard without letting water in. “Same problem as before with the regulator manifold,” he said, bracing himself to stop the swell pulling him under the boat. “My computer’s running a diagnostic.”

“I thought Kazantzakis had fixed it,” Macinnes shouted, staring imperiously at Jack.

“He did the best he could with the available tools.”

“Don’t blame us. Our remit was to host you, not to provide logistical backup. That’s your call.”

Jack gritted his teeth, trying to keep his cool. Floating here with a faulty regulator and his friend on the seabed more than a hundred meters below was not the time or place to bicker with these people. He strained his head back upward. “Costas programmed the computer to self-repair if it happened again, so I’m just waiting for it to finish.”

The man jerked his head toward the empty ocean beyond the shot-line buoy. “Does he always go off alone like that? Not the best buddy.”

Jack ignored the comment. Macinnes and Costas had barely been on speaking terms since they had arrived. Macinnes had made a big show of bowing to Jack’s superior archaeological knowledge, but had decided that he knew more about submersibles and remote-operated vehicles than Dr. Costas Kazantzakis, a big mistake. The fact that he had been unable to put down an ROV to do the preliminary recon or to accompany the dive would seem to have proved Costas’s case. Jack swung sideways in the swell, holding on with two hands. “What’s the story with the comms?”

“It’s the same story. You brought your own equipment, it didn’t match ours. Not our responsibility.”

“Is anyone on to it? I can’t communicate with Costas.”

“It’s irrelevant, with the weather getting worse. The forecast has upped from Force 4 to Force 8 in the next few hours. The last thing we need is a botched inspection and a fatality to cloud our press reports. We’ve come to pick you up.”

“Negative. I’m not leaving Costas to do the dive on his own.”

“Looks like he was quite happy to leave without you.”

Jack tried to restrain his anger. The last thing he needed before a deep dive was aggravation like this. He clicked the valve shut and pushed off from the boat, making a circular motion with his hand and pointing away as he finned back to the shot-line buoy. The crewman at the tiller looked at Macinnes, who raised his hands theatrically and shrugged. He sat back down and the crewman flipped the engine into forward, driving it in a wide arc around Jack and back toward the entry platform at the stern of the ship.

Jack reached the buoy, holding himself against the current, and looked up to see a line of crewmen wearing Deep Explorer caps along the foredeck rail. Dealing with these people over the last twenty-four hours had taught him one thing. He had seen more dull eyes and lassitude among this team than he had ever seen on a project before. He was fortunate that IMU had been a purely scientific endeavor from the outset, funded through an endowment from a billionaire software tycoon who also happened to be one of Jack’s oldest diving friends. Being here, and witnessing every discussion fall back on the hard floor of profitability, he had seen how the quest for financial gain ultimately drew the fire out of people. What drove Jack on was the urge for adventure and discovery that had pushed humans to explore since earliest prehistory, and a passion for revealing the truth about the past that could make the lowliest potsherd more valuable than any amount of gold that these people might rip out of wrecks like the one below him now.

He glanced up at the railing again, spotting a muscular figure in jeans and a checkered shirt with close-cropped graying hair, leaning on a stick. Anatoly Landor was Jack’s oldest dive buddy, the one who had been there beside him when he had taken his first breath from a diving tank in a pool while they had been at boarding school together. At first they had been inseparable, joined by their shared passion for diving, but then they had drifted apart, Jack into archaeology and Landor into treasure hunting. Landor had been an outsider at school, the son of an emigré Russian aristocrat’s daughter and a shady British businessman, and that had set the pattern for his future. Early on, before IMU had been founded, he had tried to enlist Jack into his projects, but their differences had been irreconcilable. For the past three years he had been operations director for Deep Explorer Incorporated, the investment consortium that owned the ship. The walking stick was because of a severe bend that had kept him out of the water for almost two years now.

Jack looked at him, remembering the raised arm with an okay signal that would have been there in the past, but knowing that this time there would be nothing. Landor had been a changed man since his accident, still with the upper body strength he had honed at school but with severely weakened legs, and a warning from the doctors that any further exposure to nitrogen buildup in his bloodstream — even a dive to swimming pool depth — would almost certainly result in a spinal bend and permanent paralysis. But it was not so much the physical change that Jack noticed as the hardening of his soul. Landor’s knowledge that he would have made this dive himself before his accident only increased the distance between them, fueling a resentment toward Jack that had been bubbling under the surface over the years, and was now plain to see.

His monitor was still only halfway through running the diagnostic, and he looked down into the depths again. The sea here was a strange color, green more than blue, an ominous shade, as if an ugly run-off from the war-torn countries of Africa had spilled out over the continental shelf. It could not have been a greater contrast to the azure waters of Cornwall, off southwest England, where he had been diving only three days before. When the call had come through that Deep Explorer had pinpointed the wreck of Clan Macpherson, he had just spent an hour in the shallows off the western Lizard peninsula near the IMU campus, excavating a perfectly preserved elephant’s tusk that he was convinced was part of a Phoenician cargo. He had been very reluctant to leave the site, and had spent the flight down to Sierra Leone reading The Periplus of Hanno, the account of a sixth-century BC Carthaginian explorer who had sailed these very waters off West Africa. It had reminded him of the extent of Phoenician exploration on both sides of the Strait of Gibraltar, stoking his excitement over what he had been excavating and the new story of the earliest explorers that it would allow him to tell.

The Phoenician wreck off Cornwall had been his first big project since returning from Egypt the previous year, and he was gripped by it. But a few hours in Freetown waiting for the helicopter out to Deep Explorer, seeing the state of Sierra Leone and its people, had made him realize that his priority for now had to be here. Channeled through the right humanitarian organization, the two tons of gold alleged to be on the wreck below them could make a substantial difference. The wreck was beyond territorial limits, but the IMU lawyers had suggested that a claim of ownership could be made on the grounds that Freetown was the destination of the wartime convoy and there was no documentation to show that the gold was to be transported further. It was a shaky case, but it could buy them time. At the very least, it would garner negative publicity for the salvage company and might deter investors. Nobody would want to be linked to a company that sought personal profit rather than donating a discovery of questionable ownership to one of the poorest and most war-torn countries in the world, a discovery that could provide enough to feed thousands and save countless lives.

He glanced again at his readout. Costas had been gone for ten minutes now, and still there were no comms. It would be at least another five minutes until the diagnostic was complete and he knew whether or not he could follow. He made himself focus on the objective of their dive, running through the details once more. Clan Macpherson had been a freighter of 9,940 tons’ burden owned by the Clan Line, one of the last of the great East Indies shipping companies. On her final voyage she’d had a crew of 140 men, made up of Indian Lascar ratings, British deck and engineer officers, and Royal Navy gunners to man her defensive armament. Her master, Captain Edward Gough, was a veteran of two previous sinkings, and had been decorated for his courage and seamanship. Her voyage halfway round the world from India to Liverpool was to have been a routine one, plied by thousands of ships during the war. After leaving Calcutta, she had sailed unescorted down the Bay of Bengal and across the Indian Ocean to Durban in South Africa. From there she had joined the first of a succession of convoys that were to take her up the coast of West Africa to Freetown, the staging port for ships heading across the Atlantic to the Americas or north to Gibraltar and home.

The final leg of that route, as part of convoy TS-37 between Takoradi in the Gold Coast and Freetown, should have been uneventful. The weather was fine, clear and overcast, and the 848-mile journey was expected to take five days at the convoy’s maximum speed of eight knots. The main focus of the U-boats was in the North Atlantic; it had been more than two years since a TS convoy had been struck. The escort for the nineteen merchantmen when they had left Takoradi on April 26 was little more than a token force — one corvette and three armed trawlers — and there was no air cover. Yet when the first ship was hit, when the first plume of water rose from a torpedo strike, the sight would have been sickeningly familiar to many of the seamen in the convoy. By that stage in the war the Clan Line had lost thirty-two ships — more than half its fleet — and more than 600 men, a rate repeated in the other shipping companies. Many of the seamen in TS-37 would have seen ships sunk in other convoys in the North Atlantic and the Mediterranean, and would have endured the fear of not knowing whether they were to be next.

That first strike by U-515 at 8:55 p.m. on April 30 was followed within five minutes by three others, and then a further three ships were sunk in another devastating five-minute attack in the early hours of the morning. Clan Macpherson had been the last to go, straggling behind the convoy, settling down by the head and listing to starboard. Captain Gough survived, but the ship had taken almost her entire complement of engineer officers with her when she finally plummeted to the seabed and came to rest on the edge of the continental shelf more than one hundred meters below Jack now.

Jack ran through a checklist of her cargo: pig iron, groundnuts, linseed, jute, tea. At least there was no record of munitions, other than ammunition for her own guns. Diving into wrecks with unexploded ordnance, their fuses decayed and unstable, was not usually Jack’s favorite pastime. But there was no way of knowing for sure. The discovery that she had also secretly been carrying two tons of gold had shown what could be missing from cargo manifests. For a moment, thinking of Costas somewhere below him, risking his life, Jack wished that the researcher in the archives had never found that record, and he felt a flash of anger at the salvage company and its investors. He was damned if he was going to let that gold line anyone’s pockets. He would fight tooth and nail to see it go to humanitarian relief, using the considerable weight of IMU’s board of directors and their legal team to drag it through the international courts as far as it could go.

And there was another factor that weighed on Jack’s mind, the official reason for his inspection. If Landor and the salvage company had imagined that war grave designation was something they could simply brush aside, they would be wrong. It was something else that made Jack want to spin out an ownership dispute as long as possible. New UN legislation currently in its final reading, spearheaded by IMU, would prevent salvors who transgressed from dealing with the financial institutions of signatory nations. To transgress would make them into pirates, only able to sell their finds and launder their money on the black market, making it easier for law enforcement agencies to shut them down. Investors lured into supporting them with promises of sunken treasure would pull out and put their money elsewhere. Jack was here today because this scheme was the best hope of protecting historically important wrecks in international waters. Above all, he would do all he could to protect a war grave from being plundered; persevering with the dive and making a case against Deep Explorer was his commitment to the memory of the men who had gone down with this ship on that terrible night in 1943.

He stared into the depths again. He had seen enough wrecked merchantmen from the two world wars to have some idea of what to expect. A ship that was not heavily laden could sink slowly, allowing enough time for its interior compartments to fill with water before it went down; the wreck could be substantially intact, damaged only by the torpedo strike and by the impact with the seabed. A fully laden ship that sank quickly could be another matter entirely, its compartments still filled with air and imploding as the ship sank, leaving jagged masses of metal. Clan Macpherson had been carrying more than 8,000 tons of cargo, an enormous dead weight once buoyancy had been lost.

There was one aspect of those sinkings that haunted Jack the most. Men must often have been trapped inside air pockets, alive after the ship had disappeared from the surface. Their deaths would not have been like those portrayed in Hollywood films: a final few moments as the churning waters rose, a gulp of seawater and unconsciousness. Instead they would have been horrific, surrounded by the shrieking and cracking of the hull, the air pockets lasting long enough for the titanic pressures of the ocean to bear down on them, bursting their eardrums and collapsing their sinuses, a final unspeakable agony as the ship plummeted to its grave.

Men who went to sea in ships knew full well the horrors of Davy Jones’s Locker. It was what singled them out, what made them tough. Jack came from a long line of such men, sea captains who had defended England’s shores at the time of the Spanish Armada, explorers and adventurers who had pushed the boundaries of knowledge during the Age of Exploration, merchants who had built fortunes on the spice trade with the East and the riches of the West. He himself was another, modern kind of explorer, one who had dared to go where his ancestors could scarcely have imagined, who had descended into the world of their nightmares, who had touched the void. His boundary was no longer the distant horizon that had beckoned his forebears, but he knew the same siren call of the unknown as he stared into the depths. He knew their excitement, and he knew their fear.

The LED display on his computer flashed green. The computer had fixed the fault, and the rebreather was good to go. He took a deep breath and steeled himself. It was time to dive.

2

Jack raised his head out of the water one last time and gave a thumbs-down signal for the benefit of the crewmen on Deep Explorer who were watching him. The ocean swell was now producing two-meter troughs, and he needed to get below the turbulence. He grasped the shot line beneath the buoy and pulled himself down, feeling the hiss of air into his suit as his automated buoyancy system compensated for the change in pressure, keeping him neutral. Five meters down, he was below the main effect of the swell, but the current was stronger than on the surface, pulling him out almost horizontally from the line. He clicked his buoyancy compensator to manual, pinched his nose through his visor to equalize the pressure, and grasped the line with his other hand, letting it run through his fingers as he slowly dropped spread-eagled into the depths. He had watched Costas do the same, holding on as he plummeted out of sight, and prayed that he had kept hold of the line until reaching the wreck. To let go would mean being swept off site beyond the edge of the continental shelf, and surfacing far from the ship. With no means of communication and the current trending southeast, that could only mean a long, slow ride into the middle of the Atlantic, with little chance of ever being picked up.

Jack was in his element. The tension he had felt on the surface, the slight edge of seasickness in the swell, had disappeared. As he descended further, his intercom began to crackle. “Costas,” he said loudly. “Do you read me. Over.” There was still no response. He rolled over, seeing the smudge of Deep Explorer’s hull still visible above him, then turned back to face the green-blue gloom below. He had reached sixty meters, the safe limit of compressed-air diving, and was now entering the realm where his life depended on the continuing function of his oxygen rebreather. If the glitch recurred now, before he reached Costas, his only chance of survival would be an emergency ascent using the system’s bailout regulator, a dangerous move that would put Costas beyond his help should anything go wrong. If all went well, the rebreather would allow him an hour at 120 meters, the maximum depth of the wreck indicated by the sonar. But their expectation had been for a bottom time shorter than that. All Jack needed to provide evidence for a war grave designation was to verify the identity of the wreck.

He had kept his helmet headlamps off for the descent, knowing that the beam from the thousand-lumen bulbs would cut through the gloom but also reflect off suspended particles in the water, potentially dazzling him. He wanted to accustom himself to the low light before reaching the wreck, and then only use the beam for close-up work. He checked his depth readout again: ninety meters. The gloom was enveloping him, but below it he began to sense something darker, the mottled shapes of rocky outcrops on the sea floor. Below him and just off to the right he saw the flashing red of a strobe. He felt a huge wave of relief course through him. It was a beacon, a waymarker. It showed that Costas had reached the seabed safely. Then he saw another light, a distant smudge perhaps twenty meters beyond the strobe, along the line of the drop-off where the continental shelf abruptly ended and the seabed angled into the abyss.

And then he saw the wreck. For a moment it took his breath away. The vast bulk of the ship loomed below him, its funnel gone and the superstructure a mass of twisted metal but still recognizable as a merchantman of its era. Beyond it he could see the inky blackness of the water above the drop-off, and on the other side the level plateau of the continental shelf at 120 meters’ depth. The ship had come to rest along the very rim of the shelf, upright but split in two places where the hull had impacted with ridges on the sea floor. The strobe light had been placed below the bow; the smudge of white came from one of the breaks further back in the hull. Jack sank down toward the strobe, passing the intact four-inch gun still in its mount on the forecastle, its ammunition box open and ready for use. Seconds later he came to a halt just above the flashing red beacon, seeing that Costas had jammed it into a crack in the rock in front of the 200-lb lead weight from Deep Explorer that anchored the shot line.

He kept hold of the line and let himself float with the current for a moment, taking stock of his situation. He was 124 meters deep, on the rim of the continental shelf. To his right he could see a jagged seascape of rocks extending east, a plateau that would eventually reach the African coast. To his left was the yawning chasm of the drop-off, no more than twenty meters away. The wreck was blocking the current, a south-trending flow that might exceed four or five knots in the open water beyond the drop-off, too strong to swim against. To stray out there might be to take a roller-coaster ride to oblivion, with the current sweeping down the side of the canyon and taking anyone with it to an abyssal depth before ejecting them far away, beyond the drop-off. He steeled himself, breathing rhythmically, focusing on the task at hand. He was going to have to be careful.

He switched on his headlamps and looked around. The world of gloom and shadows, a place where nothing seemed alive, had suddenly transformed into one of vivid colors and marine growth. It was too deep for most corals, but the rock was covered with living accretion and the water was filled with diaphanous organisms that reflected the light: plankton and diatoms and miniature nudibranchs. He blinked hard, adjusting to the particulate reflection, and then looked up, the two beams of his headlamp converging on the side of the hull above him. The iron was covered with rusticules, extrusions of ferrous material that seemed to drip off the hull like stalactites, with little trails of red streaming from them into the current as if the ship were bleeding. He could now see that the solidity of the wreck as it had first appeared in the gloom was an illusion — that after more than seventy years on the seabed, exposed to a powerful current, the hull plates were thin and friable, not far from crumbling entirely. The force of the current bearing on the hull meant that when the structure gave way, it was likely to be catastrophic, causing large parts to break away and be swept into the abyss. This was not a wreck that Jack would normally wish to penetrate, and the sooner they got out of here the better.

Then he saw the lettering below the port rail some ten meters above him, a few meters back from the gun mounting. It read: Clan Macpherson. It was what Jack had wanted to see, the proof that he needed. He checked his readout, making sure that the video camera on the front of his helmet was running. Those letters had probably been the only surviving remnant of her peacetime livery, as if in defiance of the gray uniformity that war had imposed on all ships. The sight of them, nearly clear of corrosion, gave him a strange sense of clairvoyance, allowing him to see for a moment the rusting hulk transformed into the ship as she originally had been. He thought of the men who had crewed her, of those who had gone down with the ship, who were still here now. More than ever he felt that the wreck was a place of sanctity, as deserving of respect as the thousands of other ships that had taken men down with them in the two world wars, whose remains were strewn across the ocean floor.

He angled his head so that his beam panned over the seabed. He could see a thin white line extending from the strobe along the port side of the wreck, the side in the lee of the current facing away from the drop-off. He reached down and gave it a tug. He guessed that it extended to where he had seen the smudge of light partway along the hull, somewhere in the green-black haze ahead.

Suddenly his intercom crackled. “Jack, are you there? Over.”

Jack felt another rush of relief. “I’m at the bow, over. The manifold glitch recurred and I had to wait on the surface for the computer to fix it. What’s the story with the comms?”

“A few moments ago I realized that the problem wasn’t with our intercom but with the diver-to-ship link. I shut that off, and hey presto.”

“So Deep Explorer can’t hear us.”

“Just you and me. Like it should be.”

“You were on your own. I was worried.”

“You won’t believe what I’ve found.”

“I saw the ship’s name.”

“It’s incredible,” Costas said. “The coordinates in the official report were dead on. Captain Gough fixed the position of the sinking with almost pinpoint accuracy, after having been torpedoed and from an open boat.”

“That doesn’t surprise me,” Jack said. “Back then they were still taught navigation in the same way as Nelson’s officers, using dead reckoning with a sextant and chronometer. The best captains had a sixth sense for it, and Gough was obviously one of those. So what have you found? And where the hell are you?”

“Jack, I need you to do something for me. I need you very carefully to look round the starboard side and see how much of the wreck is actually hanging over the edge.”

Jack looked to his left beyond the bow over the drop-off, seeing the particulate matter at the furthest extent of his beam rush by at an alarming speed, like a snowstorm caught in a car’s headlights. He finned a few strokes past the bow, feeling the edge of the current stream against his body, and peered over. In his experience, most drop-offs were not absolutely sheer, but this one was. The rock at the edge formed a jagged precipice over a darkness as forbidding as he had ever seen. To his right, Clan Macpherson’s bow rose high above him, and he could now see the starboard side of the hull hanging over the void. “Just out of curiosity, how stable is the geology?” he asked.

Costas’s reply crackled through. “The bedrock’s metamorphic, pretty friable. This cliff edge is like a snow cornice on the top of a mountain ridge. Not where I’d choose to park a ship carrying eight thousand tons of cargo.”

“You don’t want to see what I can see. From here, the hull looks as if it’s barely balanced on the edge.”

“That’s what I thought. But around the other side, where I am, you should be fine penetrating the hull providing you don’t disrupt anything. Thankfully our rebreathers don’t produce exhaust, so there’s no danger of creating air pockets that could crack any weakened structure. It’s pretty rusty in here.”

“We’ve seen the ship’s name on the bow. That’s all we need. We can leave now.”

“You’d kill me if I told you what I’d found but didn’t give you the chance to see it for yourself. Anyway, I’m in here already. You should be with me.”

“I’m trying to see the logic in that.”

“It’s called the buddy system.”

“Right.”

“Trust me. Follow the line.”

“Roger that.” Jack angled his body around, sensing the yawning chasm beneath him as the current took hold of his legs and swung them round until he was parallel with the hull. He knew that he was going to have to fin hard for a few strokes to regain the lip of the precipice, but that once he was in the lee of the wreck again, the water movement would slacken. He finned hard, but nothing happened. In a split second he realized his mistake. In the process of turning, he had allowed the current to take him crucially beyond the protective bulk of the wreck, and he was suddenly being swept along the edge of the drop-off. He felt a lurching sensation, as if he had jumped out of an aircraft, as if the bottom were falling out under him. The current had undulated downward, and he was dropping below the edge as fast as if he were riding a water chute into the void. His computer set off an audible alert and flashed red as it overrode the manual on his buoyancy system and bled air into his suit. The extra lift slowed him down enough for him to right himself and hit the alarm on the side of his helmet, activating a beacon that sent out a continuous sound-wave pulse. He smacked into something, and saw that it was a jagged lava pinnacle protruding from the cliff. He clung on to it, dragging himself up until he was straddling it, perched on an overhang between a mottled wall of rock rising high above and the sheer cliff dropping into the void below.

He looked with horror at his depth gauge: 149 meters. In a matter of seconds he had plummeted twenty-five meters below the level of the wreck. He peered at the rock face above, trying to calm his breathing. There were other protuberances, enough for handholds. It would have been a difficult ascent in the most favorable of conditions, with overhangs that would challenge the best free-climber. Down here, he was impeded by his equipment, by the current bearing down on him like an underwater waterfall, and by his inability to use footholds. He stared at his fins, fought against instinct and pressed the catch at the back of each ankle, causing the fins to draw up and mold around his calves. He would now have no chance against the current if he were swept off, but he knew they would be of little use anyway. At least now he could try to use footholds as if he were properly climbing.

He edged behind the outcrop, feeling the current slacken. There would be pockets of calm close to the cliff, beneath overhangs and inside fissures, and he needed to find those where he could. The air in his suit had caused his arms and chest to balloon out, reducing his maneuverability. He hit the manual override, bleeding off the air until he could move more freely. It was another counterintuitive decision, almost certainly sealing his fate if he were to be swept off, but it was his only chance of making any headway on the climb.

He tapped his intercom. He had heard nothing but crackling since being swept away. “Costas, do you read me. I’m at a hundred and forty-nine meters depth, over the cliff beyond the bow of the wreck, at least fifty meters southwest of my original position. I was swept over by the current and am attempting to climb back. Help would be appreciated. Over.”

There was still no response. He guessed that the rock face between them was impeding radio contact, but he knew that the sound waves from his beacon pulsing up the cliff face should be detectable by Costas’s homing device. He had to climb now, or give up any hope of survival. He released his hold on the protuberance and grasped another one above him, the jagged edges of the lava biting into the Kevlar of his glove. He pulled himself up, feeling almost impossibly heavy as he swung out against the current, every muscle in his body straining as he reached up with his other hand and found a hold. He kicked his feet back into the rock, finding a ledge and pulling himself onto it. Three meters done, twenty-two to go. He felt his heart pound, his breathing rate increase. He needed to be calm, measured, as he used to be when he had enjoyed rock-climbing, clearing his mind and focusing solely on his objective. He reached up to another handhold, and then another. Slowly, relentlessly, feeling as if he were carrying a sack of lead on his back, he fought his way up against the current, following the line of a fissure that seemed to offer the path of least resistance.

After another five meters he stopped again, his feet and hands wedged into the fissure. He tried another hold, slipped sideways and felt the current swing him around violently, crunching his rebreather backpack against the rock. He stayed still, watching with trepidation as his computer display flickered and wavered, trying not to think of the glitch in his manifold and what might trigger it again. Above him was an overhang he had seen from below but put from his mind, hoping that the fissure would continue through it. Now he saw that the fissure led into a collapsed cavern below the overhang, the remains of a lava tube. He would have to attempt the overhang like a free-climber, using only his hands, dangling over the void. Everything up to now would seem easy by comparison. He would be in the full force of the current again, fighting a downward pressure three or four times greater than anything he had encountered so far.

His arms felt heavy with the strain, and he was breathing hard. He thought of the bailout option, something he had refused to consider until now. He could let go and free fall into the void, no longer fighting the current but hoping that it would undulate back upward and spit him out above the ridge, allowing him to ascend to the surface. But that was hardly a viable plan. Even if he did make the surface, he would probably be miles away, dependent entirely on his beacon for any hope of rescue, being swept relentlessly out into the Atlantic by the heavy seas they knew were on the way. He tensed himself, focusing. He would only let that happen if his body gave way and he could physically hang on no longer. Until then, pressing on and reaching Costas was his only hope.

He pulled himself up, and hit his helmet on something. He shifted to one side, inching further up the fissure, attempting to avoid the unseen obstacle. He hit his head again, this time harder. He swung back, just in time to avoid being smacked in his visor. He stared at what was in front of him, and then felt an overwhelming rush of relief. It was an old-fashioned two-kilogram lead diving weight, suspended from a white nylon line. He looked up, his headlamp beam catching the line where it came down the overhang. He eased his feet out of the fissure, reached down with one hand to click his fins back into position and then grasped the weight with the same hand, letting go of the rock with the other and feeling the current pull him far out over the void. Ahead of him the line stretched taut to a point above the rim where he could just make out a beam of light below the bow of the wreck. He could feel himself being pulled forward, slowly but surely. The current slackened, and he was in the lee of the wreck over the rim of the cliff. He finned along the remaining length of line until he reached Costas, who had belayed it around a rock pinnacle just in front of the bows.

“Look what I caught,” Costas said.

Jack looked at the familiar stubbled face behind the visor, hardly believing what had just happened.

“The intercom went down as soon as you went over the drop-off. One of my design team in the engineering lab suggested that beacon with a magnified pulse array. All I had to do was activate my helmet display to locate it, and then go fishing. I think maybe we owe her a beer.”

“Roger that. And I’ll never make fun of you for fishing again. What other diver would carry a length of line and a lead weight with them?”

Costas patted his tool belt, then coiled the line and stowed it in a pouch. “Always be prepared.”

“Thanks, by the way. I didn’t think I was going to make it up that overhang.”

“The buddy system, remember? Always pays to have a good buddy.”

“How much time do we have?”

“How deep did you get?”

“A hundred and forty-nine meters. My readout shows my gas supply’s still good for another half-hour bottom time.”

“Twenty minutes,” Costas said. “We don’t want to extend our decompression time. Those bozos on Deep Explorer would probably leave without us. Now, where were we? You ready to see something incredible?”

Jack checked his helmet readout and did a quick self-diagnostic. His breathing had returned to normal, and any aches and pains from the climb were eclipsed by the adrenalin. He looked up again at the bow of the wreck, and then along the line Costas had laid into the gloom along the port side. If there was something good to see here, he was damned if he was going to forgo it after what he had just been through.

“How many lives do I have left?” he said.

“That was about your eighth. You’ve got plenty to go.”

“Okay. Show me what you’ve got.”

3

Costas powered ahead beside the sunken hull, the wake of his fins stirring up the silt and monofilaments that were caught in Jack’s headlamp beam. To his left the hull loomed high above, blocking off the yawning chasm on the other side. About twenty meters along the line from the bow, Costas veered inside, the yellow of his helmet disappearing from view. He had entered a vertical crack in the hull, some three meters across at the bottom and widening as it went up. Jack turned to follow, spotting Costas’s figure where the line led inside, their headlamp beams revealing a jumbled mass of structure and machinery. “Keep hold of the line,” Costas said, the intercom crackling. “I tried not to disrupt the sediment when I was in here before, but even so the visibility is poor. Some of the compartments must have imploded during the sinking, and it’s a shambles inside.”

“I don’t see any evidence here of a torpedo strike,” Jack said.

“Not here. This is where the hull split when it impacted with the seabed. The cargo holds on either side are filled with iron and manganese ore, thousands of tons of it. There’s no way the ship could have survived hitting the sea floor intact carrying that kind of weight. It’s amazing that the torpedo didn’t do that itself, but these pre-war Clyde-built ships were stronger than the Liberty ships you see splitting in half in the U-boat periscope footage.”

“Where did it strike?”

“Toward the stern, just before the number two hold. We’re going to get there by swimming beneath the deckhouse superstructure, through what’s left of the engine room. Follow me.”

Jack checked his computer display. The profile had automatically readjusted to take account of his greater depth and gas consumption during his escapade over the canyon edge, and now gave him only twenty minutes before he needed to start his ascent. The wireless connection meant that the revised data should have streamed into Costas’s computer and be showing the same profile on his own helmet readout. “Are you seeing my dive time?” he asked.

“Nineteen minutes,” Costas replied. “Once we’re finished inside, we can egress from the hole in the hull caused by the torpedo strike. Let’s move.”

“Roger that.” Jack swam cautiously into the wreckage, wincing as he felt his backpack scrape against a girder. A cloud of red from an exploded rusticle filled the water, creating a haze that restricted visibility even further. He lowered the intensity of his beam to reduce the reflection off particles suspended in the water, and looked around him. As often when diving into a wreck his focus became microcosmic, concentrating on the small details, on what he could see clearly only inches from his mask, knowing that the bigger picture might be obscured by the disorder of the structure and poor visibility. He saw a porcelain washbasin free of encrustation, and then a linked belt of fifty-caliber rounds that must have fallen from one of the gun emplacements above. He passed through a collapsed bulkhead into an enclosed space, his beam revealing twisted shapes in the darkness as he swept it around.

“We’re skirting the port side of the engine room,” Costas said. “Only about ten meters to go now.”

Jack pulled himself carefully along the line, keeping clear of Costas’s fins. A tapered cylindrical shape appeared below him, its base angled up where the retaining bolts had been wrenched away but with the dial and glass face at the other end still intact. “Did you see that?” he said. “It looks like the engine-room binnacle.”

“I checked it out when I was in here before,” Costas replied. “It’s set at one quarter ahead, twenty revolutions per minute. The officer of the watch must have ordered the ship to slow down immediately after the torpedo strike. It must have been pretty hellish down here, with the explosion having taken place just beyond the next bulkhead.”

Jack paused, floating motionless above the binnacle, remembering the report on the sinking. Amazingly, none of the men in the engine room had been killed by the torpedo strike, but four of the officers had gone down with the ship when she had finally sunk. After the strike they had volunteered to stay below to restart the engine, and to close the engine-room bulkheads against further flooding. They would have known that the ship could go quickly once the point of no return had been reached, that the slow wallowing would suddenly escalate into a terrifying maelstrom as the colossal weight of the cargo pulled her down. He closed his eyes for a moment, thinking of those men. This was their tomb, but it was also the place where they had kept the ship alive, where for a fleeting instant Jack could see the gleaming brass and well-oiled machinery instead of the sepulchral gloom and twisted shapes around him.

Costas had disappeared through a gap in the next bulkhead, and as Jack followed, he saw evidence of a different kind of devastation. Instead of damage caused by implosion and by impact with the seabed, he saw the results of a massive explosion — a space some eight meters in diameter where the ship had been disembowelled, eviscerated, leaving only the twisted ends of copper pipes and shattered steel girders jutting out around the edges. To his right he could see through the jagged hole where the hull had been blown open just below the waterline, the plates folded inward like the petals of a flower.

Below him he saw where the line had been tied off to a girder, and ahead he could see Costas straddling something in the wreckage, a long cylindrical shape, his head bent down at the far end. The intercom crackled again. “I just need to finish making this safe,” Costas said. “It’s what I was doing while you were having your regulator malfunction on the surface.”

Jack pulled himself through the bulkhead and swam up behind, staring in disbelief. “My God. You’re defusing a torpedo.”

“Fuse immunisation, to be technical. And not just any torpedo. This is a British torpedo.”

“That’s impossible. Clan Macpherson was a British merchantman, torpedoed by a German U-boat.”

“That’s the official line. But take a closer look.”

Jack inspected the torpedo’s propeller and lower body. Costas was right. The torpedo was a British Mark VIII, the standard type launched from British submarines during the Second World War. He stared in astonishment. How had this gotten here?

“I know what you’re thinking,” Costas said. “This must have been the second torpedo of a salvo, penetrating the hole in the hull created by the explosion of the first torpedo but then failing to detonate.”

“The odds against that are high, but it’s possible,” Jack said. “What doesn’t seem possible is that a British submarine sank this ship.”

“Right now, the origin of this torpedo is academic. We’ve got a more pressing technical issue.”

Jack glanced at his readout. “Twelve minutes bottom time left.”

“Okay. I need you to come up on my right side, carefully. We don’t want to dislodge this thing.”

Jack swam below a fallen girder and slowly finned forward, keeping his breathing shallow in order to maintain precise buoyancy. “Defusing Second World War ordnance is not exactly my speciality. You should know that.”

“They didn’t teach you this at Cambridge? At MIT, we got the full gamut.”

“I was researching for a doctorate in archaeology, remember? You were at MIT on a US Navy secondment to study submersibles technology. There’s a small difference.”

“You also spent two years before that as a Royal Navy diver and in the Special Boat Service. You’d have thought,” Costas continued, wrenching something and grunting, “that some basic ordnance disposal training would have been in order.”

“You’ll have to take that up with their lordships of the Admiralty. ‘By Strength and Guile,’ that was our motto. We left the technical stuff to the engineers.”

“Well, it’s a good thing you’ve got one here now.”

Jack reached a point where his head was nearly level with Costas’s chest. The zinc-coated warhead of the torpedo, the forward meter or so, had nearly separated from the main body, presumably as a result of the impact that should have detonated it. The warhead was angled upward, and Costas had wedged himself into a space above it, holding himself against a girder with one hand and trying to force a wrench around the nose cap with the other. Jack tried to edge closer, but was blocked by a mass of wreckage. “What’s stopping the torpedo from falling into the hull?”

“That girder below you,” Costas said.

“You mean the rusty one that’s nearly sheared off at one end?”

“That’s the one.”

“What do you want me to do?”

“I should be able to make it safe,” Costas said, his voice sounding strained as he leaned against the wrench. “Providing the chemicals haven’t leaked and the threads aren’t too rusted. I just need to be sure of the fuse type. I need you to get down under the rear of the warhead and read out the specs on the base.”

Jack looked down, seeing where Costas had meant. He switched his buoyancy to manual and released a few bubbles of air from his compensator, descending half a meter until he was floating just above the rusted girder. He slowly turned his head, barely breathing, until he could read the lettering under the base. “Okay,” he said. “There’s a red band across the center, which I know means it’s filled with explosive. Above the band it says ‘21-inch Mark VIIIC.’ That confirms it’s a British torpedo. Below the band, it says ‘Explosive weight 805 pounds zero ounces, gross weight 1,894 pounds 9 ounces. Date of filling, February 1943,’ two months before the sinking. That at least makes sense.”

“The explosive weight means it’s a heavy fill, more than three times the TNT fill of a standard warhead,” Costas said. “Now I need you to read out the letters immediately above the red line, below the type designation.”

“TX 2.”

“That’s what I’d guessed. It’s Torpex, fifty percent more powerful than TNT by mass, using powdered aluminum to make the explosive pulse last longer. These were real killer torpedoes, the most powerful of the war. Whoever ordered this one to be used against Clan Macpherson really wanted the ship sunk. Now I know the fuse must be a compensation coil rod contact pistol, Mark 3A. That’s all I need.”

“You don’t actually have to defuse it, do you?”

“I’m making it safe so you can see what lies below.”

“Where do you mean?”

“Directly below the warhead, in the cargo hold. Take a look.”

Jack switched to full beam, and stared down. For a moment all he saw was twisted metal on all sides and a dazzling light in the center, as if he were looking at a reflection of himself in a mirror. He dimmed the light, and gasped with astonishment. The reflection had not been off a mirror but off gold, hundreds of tightly stacked bars on pallets, filling the bottom of the hold. “Well, I’ll be damned,” he murmured. “So it was true.”

“You need to go down and take a closer look.”

“I can see enough from here.”

“The torpedo blew the tops off the crates and dislodged the bars inside the one directly below us. Trust me, Jack, you need to go down there. You need to see what’s inside.”

Jack glanced up at Costas, who was still straddling the warhead. “How are you getting on?”

“Almost done. Make sure your video is on. Just watch you don’t hit that girder.”

Jack carefully backed off, eased his way through a gap beneath the girder and sank slowly toward the gleaming piles of gold. He dropped down until his knees were resting on the bars in the nearest crate, all clearly stamped SA, for South Africa. He glanced up, seeing the silhouette of the torpedo some five meters above him, backlit by Costas’s beam, then edged over to the next crate. He could see what Costas had meant. The stack of bars had been blown apart, exposing a metal box beneath with its lid also blown off. Something lay inside, nestled in a brown material, some kind of cushioning. Jack dropped head-first as far as he could into the hole, making sure his camera was angled to catch the view. He stared, at first uncomprehending, and then he forced himself to forget the surroundings, to forget the wreck, and just focus on what was in front of his eyes.

It was a thin metal plaque about half a meter square, free of corrosion but not gold, so made of bronze or another copper alloy. It was slightly curved, as if it had once been attached to a column or a post, and had holes in each corner. The metal was beaten, not machine-made, and looked very old, far older than anything else he had seen on the wreck. The most astonishing sight was the four lines of symbols stamped into the metal. For a moment Jack wondered whether he were seeing things, conjuring up phantom images from the shipwreck off Cornwall he had been excavating only a few days before, seeing in a Second World War wreck an artifact that defied all logic or reason.

“I can’t believe I’m saying this,” he muttered, almost to himself. “But those are early alphabetic symbols, Phoenician letters of the seventh or sixth century BC.”

“I thought I recognized them,” Costas replied. “I found similar symbols inscribed on a potsherd in the Cornwall wreck on my first day excavating.”

Jack reached into the hole, trying to get at the plaque. It was no use; it was a good half a meter too deep. The only way of retrieving it would have been to remove the gold bars, but with less than five minutes left on his readout, there was no time to try. He stared at the plaque, trying to absorb everything he could see. He could just make out a strange symbol at the end of the inscription, a hieroglyph or pictogram, two stick figures with a box-like shape between them. It was something that the Phoenician who composed this had no words for, perhaps. He reached down again, heaving aside one of the bars to make sure his camera got a clear view. As he did so, there was a shrieking and grinding sound from above, and the water seemed to shake. Costas’s breathing suddenly became audible through the intercom, and when he spoke, his voice sounded distant, strained. “Jack, we’ve got a problem.”

Jack looked up, and gasped with horror. Instead of lying horizontally above him, the torpedo was now nearly vertical, nose-down. The warhead had closed back down on the main body of the torpedo, giving it the semblance of integrity, but Jack knew that it was attached by only a thin carapace of metal on one side. What was stopping the torpedo from falling further was not obvious, as the girder was nearly broken away. Costas was still straddling it, as if riding it down toward him. For a horrified moment they stared at each other, the warhead only a couple of meters from Jack’s head, hanging directly above him.

He cleared his throat. “So that’s called making it safe?”

“Jack, you need to get out of there. I can’t move, because my extra weight might be what’s giving the torpedo its grip on the remains of that girder. I need you to get to my tool belt, take out the length of black nylon line and tie off the torpedo somewhere above me, from the tail assembly.”

“Are you telling me that line has at least a two-ton weight rating?”

“One ton. But it might buy us time.”

Jack injected a small blast of air into his compensator and rose slowly out of the crate to the level of Costas’s belt. His readout began flashing amber, a warning that he had only two minutes of bottom time left. He knew where the line was kept; he opened the pouch and extracted it, then ascended past the girder to the torpedo’s tail fin assembly. He looped the rope twice around the cylindrical propeller guard and up over two massive girders above him, then repeated the loop with the remainder of the rope, tying it off at the torpedo. His computer began flashing red. “Done,” he said. “If this holds, the torpedo should hang free. But even if it does hold, I can’t see it lasting long.”

“I’m letting go now. Then we’re out of here.” Costas let go with one hand, injected air into his compensator, and then released the torpedo completely, floating free above it. There was a sickening screech as the torpedo slipped another half-meter down the rusted girder, pulling the line taut. One of the loops snapped, whipping and coiling in the water. Jack turned away and powered toward the opening in the side of the ship, followed close behind by Costas. As they cleared the hull, there was another ominous creaking sound and a shimmer in the water. Jack watched his warning light revert from red to amber as they ascended the rocky ridge outside to the level of the continental shelf. “At least you managed to defuse it,” he said, watching Costas come alongside. “Not much chance of that thing blowing without a fuse, I would have thought. Still, good to be cautious.”

Costas cleared his throat. “Well, it didn’t go exactly as planned.”

“What do you mean?”

“The threads were really rusty. You would have thought they might have coated them with zinc, too. Wartime British expediency, I guess.”

“You’re saying you didn’t defuse it.”

“Not exactly.”

“Even so, there’s not much to worry about, is there? It didn’t go off in 1943, so it probably won’t go off now. It was a dud.”

“Well, when I said not exactly, I meant I didn’t defuse it, but I did make some progress. I did manage to arm it.”

Jack’s heart sank. “You what?”

“It wasn’t a dud. The torpedo mechanic who was meant to arm it didn’t screw the fuse in far enough. It was a new type in 1943, and he was probably not that familiar with it. I tried it, just to see, and it went active. Problem was, I couldn’t screw it back out again.”

“Great,” Jack said. “So we’ve managed to leave eight hundred and five pounds of high explosive hanging by a piece of string from a rotting girder, armed with a live impact fuse.”

“We’re due for our first ten-minute decompression stop now, at ninety meters. I suggest we get behind this rocky ridge, where we should be protected from the shock wave. Stopping in the middle of the water like we are now is probably not such a great idea.”

“Can’t be too safe, can we?” Jack muttered, leading them behind the ridge. At that moment there was a huge rending sound, like a deep groaning, and then silence.

“That would be the girder. Next will be the rope. Hold me, Jack.”

“Finally lost your nerve?”

“Less chance of one of us being blown through the water. Might be a good idea to activate our ear defenders now.”

Jack quickly pressed the sides of his helmet, muffling the sounds from outside, and then clung face-to-face with Costas as low as they could go against the seabed, huddled together behind a rocky pinnacle. A moment later he seemed to be lifted bodily from the seabed, and the water shook violently around them. The sound of a huge detonation followed, a massive muted boom that seemed to course through him. A large fragment of rock tumbled down from the top of the pinnacle and landed beside them, followed by an avalanche of smaller fragments. There was a strange silence for a few moments, followed by an indescribable cacophony, a creaking, screeching and groaning noise as if an orchestra of industrial machinery were tuning up. Then, with a lingering, fading shriek, it was gone, leaving an eerie silence.

“That would be the ship,” Jack said quietly after a few moments. “Falling five thousand meters into the abyss.”

Costas gazed at him through his visor, wide-eyed. “Whoops.”

Jack stared back at him, the water still shimmering between them. “Whoops. Is that all you’ve got to say?”

“So that’s what it’s like to be underwater when a torpedo goes off,” Costas continued, his eyes glazed in wonder. “Cool.”

Jack watched his computer readout flicker, and then stabilize. “The explosion doesn’t seem to have restarted my manifold glitch, thankfully. Not sure I can say the same about my nerves.”

“Did you feel that shock wave?”

“It’s a good thing we were behind this ridge, otherwise it would have killed us.”

“We’d have been dead anyway,” Costas said. “There was enough force in that blast to have ripped our arms and legs off.”

“Why does something like this always happen when I dive with you and there are explosives involved?”

“It’s called science. What IMU is supposed to be all about,” Costas said. “Hypothesis, experiment, observation. Anyway, it solves the problem of who gets the gold, doesn’t it? The floor of that canyon is well over a mile down, with who knows how much depth of sediment lying on the bottom. The chances of our Deep Explorer friends finding even one of those gold bars again would be pretty close to zero.”

“They’ll have registered the shock wave on the surface,” Jack said. “We’ll tell them the wreck contained a consignment of ammunition. There was no record of that, but then there was no record of the gold, either. There were lots of secrets in the Second World War, and this is what happens when you mess with them. I’ll radio the Ministry of Defense in London and our UN representative to say that we saw enough to identify the wreck as a war grave, but that they have nothing to worry about, as there’s no way the salvage company can now get at her.”

“You won’t mention the torpedo?”

“That it was British? That’s between you and me, for now. There was something strange going on here, something that might have involved the gold and that plaque, and I want to try to get to the bottom of that first.”

“We didn’t exactly not interfere with a war grave, did we?”

“The torpedo should have gone off in 1943. It was going to fall through those rusting girders anyway, and the wreck wasn’t going to last long on that ridge. It’s all part of the natural process. All we did was help it on its way.”

“And nobody’s lifted anything from the wreck. Davy Jones’s Locker remains sealed.”

“Amen to that.” Jack looked up, seeing the distant smudge of light from the surface, the shot line bowing above them in the current. His computer flashed green, and he followed Costas up to their next decompression stop, looking down as he ascended and seeing the gloom envelop the seabed. The only evidence of a wreck once having been there was a storm of silt spiraling up from the drop-off, like a huge twister in the sea.

Costas hung on the line, turning to Jack. “What else do we tell our friends on Deep Explorer?”

“What else is there to tell? Did you see any gold?”

“Not a glint.”

“And your camera malfunctioned.”

“Yours too. Faulty IMU equipment. They’re used to that.”

“Pity about your plan to get the gold to Sierra Leone, though.”

“There might still be something good out of this. The guy I went to have lunch with in Freetown while you were sorting out our equipment was an old friend, a former army officer who works for a relief agency. After Rebecca did her stint with UNICEF in Ethiopia last year, I began to think about how I might contribute.”

“Taking the cue from your eighteen-year-old daughter? Isn’t it supposed to be the other way round?”

“You know Rebecca as well as I do,” Jack said. “She’s been plowing her own furrow for quite some time now. Anyway, it’s about logistics, organization, the kind of thing I can do well, driving a project forward. I even mentioned the combat medic course I had to do in the Royal Navy when I went into the Special Boat Section. A bit rusty now, but I could update.”

“You telling me you’re going to volunteer for a relief agency?”

“I was just sounding him out. It would only be a couple of weeks a year, between projects.”

“Have you spoken to Ephraim about this?” Costas asked. “I have to remind myself that he’s not only IMU’s main benefactor but also runs one of the largest charitable foundations in the world. After providing IMU with its endowment, he gave away ninety percent of his remaining assets to charity. It’s the kind of thing a software tycoon can do and still remain seriously wealthy. When he’s not diving with us, he’s pretty well full-time with his foundation.”

“I talked it through with him when Rebecca first showed an interest. He said the best thing that people like us can do is to provide motivational and leadership skills, to enthuse and inspire. That’s something money can’t buy.”

“Rebecca would be proud of her dad.”

“She’s too busy even to think about what I’m up to.”

“Let’s see,” Costas said. “Before Ethiopia, she was exploring the hidden libraries of the Mount Athos monasteries in Greece with Katya, after working with her on the ancient petroglyphs site in Kyrgyzstan. How is your old girlfriend, by the way? Ever think of giving her a call?”

“We haven’t got external comms down here, remember. Just you and me.”

“I don’t mean now. I mean topside, with that phone you usually keep in your pocket.”

“Katya keeps me in the loop. When Rebecca’s with her.”

“Huh. Anyway, Rebecca hardly paused for breath after Ethiopia before joining the dig at Temple Mount in Jerusalem, and then flying out to Seaquest in the Mediterranean to help Maurice and Aysha sort out the material they’d managed to rescue from the Institute of Archaeology in Alexandria prior to the extremist takeover in Egypt.”

“My turn to be proud of her,” Jack said. “Maurice is really her honorary uncle, just like you. Egyptology was his life and he was devastated when they had to leave Egypt, really unable to cope. Rebecca being there meant that Aysha could return to London to look after their son. Rebecca was the one who diverted his attention to Carthage, to the old idea he had when he and I were at school together, that it was not the Phoenicians but the Egyptians who had gone west and founded the first colony there. I still don’t think he’s right, but Rebecca and I encouraged him to check it out on the ground because it gave him a new focus. He’s been digging in Tunisia for over a month now, and Aysha’s been able to join him again.”

“Lanowski’s even torn himself away from his computers and gone out there.”

“He’s been a good friend too. Everyone’s rallied round.”

“And now Rebecca’s been back with Katya in Kyrgyzstan for the final season there.”

“She’s like I was at her age. Doing as much as she can. It’s great drawing off that zest for life, for new experiences.”

“Are you going to discuss your plan with her?”

“Once we know we can finance it. Until then, the fewer people who know, the better. But we do often have a bit of time between projects, don’t we?”

“Speak for yourself. In the engineering department it’s 24/7, three hundred and sixty-five days a year.”

“Ephraim thinks you could use a break too.”

“I’ll think about it. Yeah, I could do that too. You’d need someone to watch your back, for a start. Some of those places are pretty dodgy. But right now, we’ve got to make sure we’re not swept away into the middle of the Atlantic Ocean. Time for the next deco stop.”

“Roger that.”

Jack made his way hand over hand up the line behind Costas. At thirty meters he looked down one last time, seeing the billowing silt cloud where they had been exploring only a few minutes previously. Costas had been right. That truly was Davy Jones’s Locker, a place where nobody living belonged. He looked up, seeing Costas hanging on the line above him, a glint of sunlight reflecting off his helmet, and above that the dark silhouette of Deep Explorer rolling and pitching in the swell. He remembered the plaque, and felt a sudden rush of excitement. The wreck might be gone, but their discovery had left indelible questions in his mind. What was a Phoenician antiquity doing concealed in a secret consignment of gold on board a Second World War British cargo ship? What was a British torpedo that could only have been fired from a British submarine doing inside the wreck?

Twenty minutes later, Costas tapped his wrist, and gave a thumbs-up. “Deco’s over, Jack. We’re clear for the surface. You good to go?”

Jack checked his display. “Good to go.” He followed Costas slowly up the line, his body dragged nearly horizontal by the current, feeling the pull of the buoy as it bobbed in the swell. It was going to be a tricky egress into the Zodiac, and there might be an ugly confrontation with Landor and the salvage team over what had happened to the wreck. But he was already racing ahead to the next few days, to what he would do when he got back to IMU headquarters. He prayed that the images from their cameras would be clear enough for analysis. He needed to get the footage to his colleagues Jeremy Haverstock and Maria de Montijo at the Institute of Palaeography in Oxford. He would take them himself, and combine them with a study of Phoenician artifacts in the Ashmolean Museum. And he would go to the National Archives at Kew to dig up anything more he could find out about Clan Macpherson and convoy TS-37: any further cargo and crew manifests, secret directives from the Admiralty, German U-boat orders that might have been intercepted and decrypted at Bletchley Park and sent on to the convoy commodore, anything that might help to solve the mystery of the wreck and its cargo.

They reached the chain that held the shot line to the buoy, and then clawed their way up until they broke surface. Jack grasped one of the rope loops around the buoy and glanced up at Deep Explorer, seeing the crewmen lining the foredeck looking down on them. He raised his free arm in the okay signal, and saw Costas do the same. The swell was pulling the buoy dangerously close to the hull, and he hoped the captain would have the sense to release his anchor line now that they had surfaced, and to stand off while the Zodiac attempted to pick them up. He glanced toward the stern of the vessel, seeing the Zodiac still raised on its davits. After sensing the detonation, they would have kept the inflatable out of the sea until they knew what was going on. They could hardly have expected them to return from the wreck alive.

Jack tapped his intercom, making sure it was still working. “We’re going to have to open up ship-to-diver comms to give them guidance. The ship’s going to have to stand off, for a start. The swell’s a lot stronger than it was when we went down. Having survived that dive, I don’t want us to end up crushed between the Zodiac and the ship’s hull.”

“Roger that,” Costas said. “Anything else before they’re able to listen in on us?”

“Here’s my plan. Once we’re on board, I’m going to radio my friend in Freetown to see if he can get a Lynx helicopter from the British military mission to come out and pick us up pronto. He’s ex-army and I’m still a reservist, so he can make it official. British naval officer and American colleague need rescuing from the clutches of pirates, or something like that. Otherwise, with the weather worsening, I can see these guys on Deep Explorer refusing to fly us off in their own helicopter, using the weather as an excuse to grill us about what we saw. Landor will think he knows which buttons to press to try to get me talking, but I’m damned if I’m going to give him that chance. He and I are way past swapping dive stories now. And the last thing we want is for them to snatch our cameras and see those images of the gold. There’s not much they can do now to recover it, of course, but they could make life very unpleasant for us. We need to get out of here as soon as we can.”

“Roger that. Ship comms back on line in two minutes.”

Jack twisted around so that he was floating on his back, the spindrift from the waves lashing his visor. By the time they reached Freetown and had stayed a night with the military mission, their nitrogen saturation levels should be safe enough to fly. He would also put in a request for the IMU Embraer to fly down from England and be waiting for them at Freetown airport.

He felt bone-tired, but exhilarated. He needed to get home, to transport himself back to the darkest days of the sea war in 1943, to a time when the future of the world hung in the balance.

He could hardly wait to see where this mystery would take him.

4

A bitter wind swept across the forecourt of the compound, and the woman drew her coat more tightly around her as she hurried toward the checkpoint in front of the entrance. It had only been a twenty-minute walk from the station, but already she was beginning to miss the fug of the train compartment, the familiar smell of stale sweat and wet wool and tobacco, the warmth of the men around her. Most were bomber crew back from weekend passes in London, some still fuddled with hangovers but others pale and wide-eyed and staring through the window into the pre-dawn darkness, knowing what lay in store for them in the skies to the east. At Bletchley they had stayed on board while the train disgorged its other passengers, the silent army she could hear coming up the lane behind her. Many were women, civilians like her or girls of the Women’s Royal Naval Service, with a few male army and naval officers among them. As usual she had hurried ahead to avoid lining up in the cold at the checkpoint, and to be the first for a cup of tea at the NAAFI canteen inside.

She reached the barrier and stopped in front of the two military policemen in greatcoats with rifles and fixed bayonets. A corporal came out of the booth, blowing on his hands, and stood before her. “Papers, please.”

She knew the drill, and already had her ID, clearance papers and weekend pass in hand. He scrutinized them and then handed them to the officer who had come out of the booth behind him. “Name?” the officer demanded, towering over her.

She drew down her scarf from her chin to show her face, and looked up at him. “Fanny Turley.”

“Occupation?”

“Civilian telegraphist clerk, Admiralty.”

“What were you doing in London?”

“Staying with my sister in Clapham.”

“But your papers give your home address as Shropshire. Why not go there?”

“My sister’s husband has just been killed in Burma.”

“Did you talk to anyone about your work here?”

“No.”

“Did anyone not working here accompany you to Euston station?”

“No.”

“What’s your division?”

“Hut 9b, Special Operations. Atlantic convoys.”

“Supervisor?”

“Commander Bermonsey.”

The officer passed back her papers and nodded her through. He had not shown a flicker of recognition, despite the fact that he had spent an evening the week before trying to chat her up in a pub in the nearby village where she was billeted. He was a professional, as they all had to be in this place. The slightest chink in the armor, the slightest lapse in security, could see the whole code-breaking edifice crumble before their eyes.

Even her family had no idea what she was doing. When she had abruptly left her job as a schoolteacher in Shrewsbury to work for the Civil Service in London, they had guessed that it might have had something to do with her aptitude for math, but when they asked her, she had revealed nothing more than her job title and that she worked for the Admiralty. Her sister knew that she was based somewhere an hour or so to the north of London, but that was true for so many girls employed in government departments that had relocated to country houses following the Blitz. Her job title, telegraphist clerk, was a typical Bletchley cover, revealing nothing of her true role. Even within Bletchley there were multiple veils of secrecy, with those in one hut knowing little of what went on in the hut next door. But everyone who worked here knew the official name of the establishment, the Government Code and Cypher School, and even the military policemen outside who knew nothing of decryption were aware that keeping this place secure was vital to the war effort.

She pushed through the door, grateful for the surge of warmth, went straight over to the canteen, and took one of the mugs of sweet tea that were already being laid out. For a few precious minutes she could ignore the smell of watery cabbage and burned fat that seemed to permeate the place, a residue of lunches past and a foretaste of delights to come. She nestled the mug in her hands for a moment, blowing on the tea, before heading off to the door that led out to the central courtyard and toward the huts, knowing that those coming through the checkpoint behind her would soon be crowding around the canteen.

As she stopped to take a sip, an elegantly dressed young woman came out of the lavatory door beside her, finished applying lipstick, and then snapped shut her handbag, smiling. “Hello, Fan. Good leave?”

“Euston was absolutely packed, even at six A.M.,” Fan replied. “There must be quite a lot more new recruits among this lot behind me. I see they’ve already begun work extending the compound to the north while I’ve been away. Soon we won’t be able to see the old park at all for the Nissen huts.”

“There are more Americans here now. Several new ones in your hut.”

Fan shrugged and drank some more of her tea. “Can’t say I’ve noticed.”

“Come on, Fan. It’s an open secret you’ve got two new American officers. One of them looks quite dishy.”

Fan shrugged again, smiling innocently. “I couldn’t possibly comment. Top secret, you know.”

“You’re hopeless. By the way, your Commander Bermonsey knows we’re billeted together and has been asking for you. He was here ten minutes ago, chomping at the bit. He wants you to go straight in as soon as you arrive, lickety-split.”

“That’s why I made sure to take the first train back. He’s always like that.”

“This time might be special. He was just like my CO gets in Hut 8 after he’s been at work through the night, all jittery and nervous. My guess is there’s something big on. Just a friendly warning.”

“All right. See you this evening in billets.”

“With a dishy American in tow, just for me?” She grinned, waved her handbag, and was gone, sauntering out of the door toward the complex of huts adjoining Bletchley House, the stately home that had been the sole building in the park before the war.

Louise Hunter-Jones was from a very different social background to Fan, with a posh Mayfair address, and her frippery could sometimes be trying. But what both girls shared was an aptitude for math, something that had led Louise to Girton College, Cambridge, and Fan on a scholarship to the University of Birmingham, and both had been snapped up by Bletchley when the recruiters had contacted university departments looking for recent graduates with first-class degrees, women as well as men. Louise had gone straight in with the naval code breakers in Hut 8, but then had been transferred to supervise one of the bombes, the inscrutable name given by the Polish intelligence people who had invented them to the electromechanical monsters that churned through the permutations to find the daily settings for the German Enigma machines, clattering and shuddering and reeking of machine oil. It always left her pale and drained at the end of the day. For a while she let it be known that she felt she had drawn the short straw, but then her natural enthusiasm took over and she had made the best of it; the extra effort she took with make-up and clothing was part of that.

Fan, by contrast, had become a statistician, a calculator of probabilities, an adviser to the officer in charge in her hut when they needed to estimate how many of the deciphered U-boat orders they could act on without raising suspicions among the Germans that Enigma had been broken. She did not end each day with her ears ringing and her clothes reeking as Louise did, but dealing with statistics and probabilities took its own toll, the knowledge that what she was doing was not just about saving lives but also making decisions not to, and letting men on the front line in the Battle of the Atlantic sail on into probable destruction and death.

She pushed open the door and started to make her way across the courtyard beside the central pond, the mansion ahead of her and the rows of long wooden huts where most of them worked to the right. Hearing a familiar light step coming quickly up the path behind her, she turned and watched the runner approach. He was wearing only a vest and shorts despite the cold, and his dark hair was matted to his forehead.

“Hello, Alan,” she said. He swerved off the path and came to a halt on the grass beside her, his hands on his knees, panting hard. “Good run?”

He looked at his watch. “Better than last time. Set off at midnight.”

“At midnight?” she said incredulously. “From where?”

He looked up at her, nonplussed. “London, of course. Whitehall, to be precise. Had a meeting.”

“You ran all the way here from London? At night? In the blackout?”

“Best time for it. No traffic on the roads. Anyway, it’s a full moon.” He peered up at the clouds. “Allegedly.”

“That’s more than fifty miles.”

“Early-morning trains are always too crowded these days. Running clears my head.”

“You’re mad.”

He gave her an impish grin. “So they tell me.”

“Let me at least get you some tea.”

He shook his head, then nodded toward the huts. “Quick shower, then I’m back in there. Work to do.”

“Louise thinks there’s something on. Bermonsey’s been looking for me.”

His breathing eased and he straightened up. “You know, it was easier earlier on in the war when it was just code-breaking. Then it was a mathematical problem, an exercise in scholarship. Now it’s different.”

“I know what you mean,” she said. “Now it’s real people, real lives.”

He stared up at the sky, his hands on his hips, and shut his eyes, the sweat running down his neck in rivulets. Then he looked down and gave her another grin. “See you in the machine.”

She watched as he jogged off to the shower block beside the mansion. He had taken to calling their workplace that, the machine, after someone had dubbed him deus ex machina, the god from the machine, the device in a storyline that saves the plot. Alan Turing had done that, had done incredible things, had made Bletchley work, but now he was no more than the rest of them, a cog in a machine where genius mattered less than the ability to see human lives as little more than chess pieces, as dispensable elements in the calculus of war.

She turned toward the row of low buildings that formed one edge of the compound. They called them huts, but in reality they were a lot more than that: long, purpose-built structures of interconnected offices and workspaces that could hold a hundred or more workers each, both civilians and service personnel. Hers was officially Hut 9b, but was known informally as the special operations hut. She thought about what Alan had said. More and more, this damp corner of Buckinghamshire seemed to be at the forefront of the war. Sometimes, hunched over the map table, choosing one convoy to save over another, it seemed as if the raging Atlantic were just outside, as if opening the door would reveal the mountainous seas and howling wind, the dark shapes of ships and the throbbing of engines as they battled through the night.

She shivered, and remembered the bomber boys on the train. They were someone else’s responsibility, other girls like her and Louise in another secret place, pushing counters across a map, sending some men to near-certain death and giving others a temporary reprieve. She could do nothing to help them. Her boys were the men at sea, the thousands of sailors in merchant ships, British, American, Canadian, Norwegian, Indian and all of the other Allied seafaring nations pitted against the Nazis, plowing their way across the Atlantic and running the gauntlet of the U-boats, living in constant fear of attack. Her twenty minutes in the chill air this morning was nothing compared to the cold felt by those men out there tonight, their ships pitching and rolling as the spray lashed them, trying to maintain station in the darkness. Keeping some of those men alive was what kept her coming back here, day after day, night after night.

She looked up, seeing the milky smudge where the light of the moon was now visible through the morning clouds. The full moon that had guided Alan on his run might be silhouetting those ships in the darkness to the west, making them easier targets for the U-boats. She prayed for cloud over the Atlantic, for rain. She took a deep breath and steeled herself, the adrenalin already coursing through her. She could hear others coming up the path behind her. She pushed open the door and stepped inside.

Fan doffed her coat and warmed her hands at a radiator in the main operations room while she waited for Commander Bermonsey, who was bent over a map table conferring with the two US Navy officers who had so intrigued Louise. They were part of the increased numbers of Americans who had come to Bletchley over the past few months in advance of the planned handover of a large part of the Ultra decryption work to US naval intelligence in Washington. Bermonsey straightened up and saw her, but continued talking to the men. He was awkwardly tall for a submariner, she thought, well over six feet, though with his thick beard and gaunt, handsome features he looked the part. They had been told that before being posted here, he had been the sole survivor among the captains in his flotilla out of Malta, and that his boat had been lost with all hands on its first patrol without him. He had been jittery when he had arrived, pale and haunted, but once he had settled in, he had begun to run the operations room as if he were on the bridge of a ship, something that Fan found she relished; it gave what they were doing the urgency of the life-and-death decisions that she knew he must once have faced at sea.

He strode over to her. “Good. You’re here. Follow me.”

“Sir.”

As a civilian, she was not obliged to show him military deference, but she did so anyway. It helped to keep the nature of their relationship clear, and it was more comfortable for him. She guessed the drill for the morning, because it was the same every morning. First they would go to the main chart table, where the night’s decrypts would already have been whittled down to two or at the most three possibilities. There would be an open discussion, and she would provide her analysis. Next, she and Bermonsey would go to the closed operations office at the other end of the hut, where he would make the final decision. At a pre-appointed time, Bermonsey would pick up the phone and call a secret office in the Naval Intelligence Division of the Admiralty’s Operational Intelligence Center, where the advice from Bletchley would be recast as the commander-in-chief’s orders and sent to the commanding officer, Western Approaches, in Liverpool, or directly to the convoy commodores themselves. Within twenty minutes of Bermonsey picking up the phone, the helmsmen in the ships of the chosen convoy would be changing course. Nobody outside this room would know which other convoys that could have been saved had been sacrificed for the greater good. The steps in the procedure were always the same, like the ritual of a dawn execution, one always with the possibility of a last-minute reprieve.

Fan knew that Bermonsey was in an extraordinary position. As a mere commander, an acting rank at that, he should not have had the authority to issue orders to the highest echelons of the Admiralty. Officially, therefore, his messages to the OIC following these meetings were couched as advice, to be acted on further up the chain if the rear admiral commanding OIC saw fit. Unofficially, his messages were translated into operational orders without exception. Churchill had taken Alan Turing and his team under his wing when he saw that their efforts might be thwarted by those who disliked “boffins,” and had issued a personal directive that the outcome of all that effort was not to be hindered by military red tape. Anyone higher up in the Admiralty who kicked up a fuss was removed, instantly. Fan knew that the judgments made in this room were tantamount to orders from the commander-in-chief himself.

She followed Bermonsey to the chart table. She could see that he was on edge, that his hand was shaking slightly as he opened a file. He was probably running on empty again, fueled by tea and cigarettes. Beside him stood Captain Pullen, a retired officer who had done Bermonsey’s job during the latter stages of the Great War and had been re-employed to be in charge of the day-to-day running of the hut, but without authority over the Ultra output to the Admiralty. Around the table were a dozen others: girls like Fan, several naval officers, and two of Turing’s team who had been shuffled here to make use of them after the main decryption breakthrough, both of them disheveled young men who looked as if they had walked straight out of a Cambridge common room.

The two Americans came and stood in the wings, watching while one of the junior Royal Navy officers arranged some gaming pieces and pencils on the pinned-up chart of the Atlantic in the center of the table. Fan glanced at the shuttered window beside them, seeing that the sun was breaking through. It had been another long, hard winter, the fourth of the war. For the first time she had sensed a cautious optimism while she had been in London over the last few days. The tide had finally turned in the campaign against Rommel in North Africa, and on the Russian front; in Britain, the huge build-up of troops and equipment could only signal imminent invasion plans. And yet for the men actually on the battle lines, that optimism would probably have seemed far-fetched. For those at sea, winter might be over, but the Atlantic was still swept by gales and cold enough to kill a man in minutes. For those men, her men, men who so rarely saw the enemy but who lived in his shadow day and night, the war went on, relentless and unchanging, the dark angel of death ever-present just beneath the waves and over the horizon.

Bermonsey glanced at the wall clock, and then at his watch. “Right. 0630 hours. My phone call to the Admiralty is scheduled for 0715. You have fifteen minutes for your assessment. Lieutenant Hardy?”

The naval officer opposite Fan who had laid the counters on the chart sat down and arranged his papers. He was about her age, a recent arrival from the Operational Intelligence Center, one of two officers at the table whose job was to provide a naval briefing to complement her own more mathematical analysis. He had only been here a few weeks, but had already acquired the distinctive flushed, pallid look of long-term Bletchley inmates, a consequence of too little sunlight and too much time in smoky, overheated rooms. He picked up a ruler and leaned over the table, pointing at the map as he spoke.

“The Ultra intercepts from last night reveal three U-boat patrol lines in the North Atlantic, here, here and here,” he said, tapping the map in three places. “To the south, a line the Germans have code-named Amsel, meaning blackbird, comprising eleven U-boats. To the east, off Greenland, Meise, blue tit, thirty boats, covering the northern route. And finally on the western side of the mid-Atlantic air gap, Specht, woodpecker, seventeen boats, arranged in a line running south of Greenland.”

“No wolf packs?” Bermonsey asked.

Hardy shook his head. “No wolf packs. These are not roving attack formations. They are strung-out, static lines, like fishing gillnets.”

Bermonsey pursed his lips. “And the convoys?”

Hardy moved the pointer from the pencils indicating the U-boat patrol lines to the backgammon pieces he had arranged across the map. “As of 0500 hours, there were some three hundred and fifty merchant ships in the North Atlantic. Most are within the Western Approaches or off the North American seaboard, well within air cover. The two mid-Atlantic convoys that should concern us most are SC-127 and ONS-5. Patrol line Meise was deployed to catch SC-127, but three days ago the convoy slipped through a gap in the line, completely undetected. SC-127 is by far the biggest prize in the North Atlantic at the moment, an eastward-bound convoy carrying US troops and military supplies for the invasion build-up. But we think it’s safe.”

“And the other convoy?”

“ONS-5 is westbound, so the ships are mainly in ballast. German naval intelligence knew it was en route, not from decrypting our messages but from long-range Luftwaffe Condor patrols out of Norway that were shadowing it. Having let SC-127 slip through the net, patrol line Meise was ordered two days ago to reconfigure to catch ONS-5. Yesterday we intercepted a message sent by a U-boat at 1650 hours showing that they had sighted the convoy. We assume that since then the patrol line will have been constricting, tightening the net and making it less likely that this second convoy will slip through. The Germans won’t want to make the same mistake twice.”

Fan peered at the young officer. Another secret, another fold in the veils that fortified Bletchley, something that even those around this table were forbidden to voice, was that Turing’s team had known for some time that their German equivalent, B-Dienst, had broken the British naval cypher used for Allied North Atlantic convoy messages. As a result, not only was Bletchley playing a game of cat-and-mouse with the Enigma decrypts, pushing and prodding to see how much they could get away with, but they were also playing a similar game in the other direction, keeping the compromised British naval cypher open and using it to feed disinformation to the Germans. They had pushed their luck to the point where B-Dienst would be bound to rumble them soon, so a new naval cypher was ready to be activated. But meanwhile the game with B-Dienst went on, seeing how far they could go in acting on their knowledge without exciting the suspicion of their counterparts in German naval intelligence somewhere deep in their own secret operational headquarters outside Berlin.

Bermonsey stood forward, leaning on the table. “What’s the strength of the escorts?”

“Mid-ocean escort force group B-7,” Hardy replied. “A strong group, British, Canadian, American, some of the best corvette captains we have. They’ve been buoyed by their success in depth-charging U-boats over the last few months, and frankly, they’re spoiling for a big fight. This could be their chance to score a decisive blow, with twelve or more U-boats in that patrol line converging on the convoy and those other patrol lines also within striking range. If the escorts can sink or disable half of those U-boats, then the pendulum really begins to swing in our favor. The Germans simply can’t build enough U-boats to make up for losses like that, or replace the experienced crews.”

Bermonsey tapped the table with a pencil. “So if we did interfere with ONS-5 and send a warning, we could be preventing a convoy battle that might change the course of the war.”

“And even if we did warn them, there’s the problem with strung-out patrol lines that they may be too long for a convoy to sail around, and in so doing the convoy might be exposing itself to other U-boats in the area. As you know, it’s different with a mobile wolf-pack flotilla or a lone U-boat, where we can attempt to calculate their course from the intercepts and reroute a convoy out of danger’s way. If you try that with a patrol line, you’re just as likely to reroute the convoy into another submarine further down the line.”

Bermonsey nodded. “And as a westbound convoy, with the ships in ballast, ONS-5 is a lower-order priority than an eastbound, laden convoy. As bait for a potentially decisive U-boat battle, the ships in that convoy can therefore be considered expendable.”

He paused, looking round for any retort. Fan thought about what he had just said. A lower-order priority. She knew the fate merchant seamen most feared, being torpedoed in a heavily laden ship, knowing they could go down in seconds. But they could be just as vulnerable to torpedoing in an unladen ship, when they were less likely to have a guardian angel watching over them. And in the scenario they had just been contemplating, one that would depend on ships being hit in order for the escorts to know where to take action, the merchant seamen would be mere pawns in the battle.

“That’s the North Atlantic done, then,” Bermonsey said. “It leaves ONS-5 as our one open file, but with the tactical assessment pointing to inaction. Agreed?” There was a general murmur of consent, and he looked at the other seated naval officer. “And now for the South Atlantic.” He glanced at the wall clock. “Make it snappy, if you please.”

The other man, a lieutenant commander in the Royal Naval Volunteer Reserve who looked as if he might have been an academic in civilian life, pushed up his spectacles and peered at the lower half of the map. “It’s more straightforward, thankfully. The other actionable Ultra intercept of the past twenty-four hours concerns U-515, which is heading south off the coast of West Africa on a collision course with convoy TS-37, heading north from Takoradi in the Gold Coast to Freetown in Sierra Leone. A couple of ruled lines on compass bearings give the point of contact at about 35 degrees 15 minutes north, 45 degrees 12 minutes east, about fifty miles off the coast of Sierra Leone.”

Fan spoke for the first time. “Do we know whether U-515 has intelligence on TS-37?”

The officer looked up. “It seems so judging by the intercept course, though we don’t know how. TS-37 is one of the convoys we’ve chosen not to contact using the compromised Naval Cypher No. 3, but we suspect the existence of a Nazi spy operation in Durban who may be able to pass on information about convoy departures. Four of the ships in the convoy are carrying large consignments of manganese ore, currently in very short supply for steel and aluminum production and desperately needed to keep production of bomber aircraft up to counter the losses we’ve been enduring. The current directive from the Ministry of War Transport is that those cargos are to be considered of higher value even than munitions. Manganese is so valuable that you’ll see it disguised as pig iron in the cargo manifests of some of those ships in order not to attract the attention of spies whose information might feed back to U-boat headquarters. Corabella is carrying eight thousand and sixty tons of manganese ore; Bandar Shahpour three thousand tons. Clan Macpherson has over eight thousand tons of it, all described as pig iron. In the past, TS convoys have only rarely been hit, with Admiral Dönitz’s attention mainly having been in the North Atlantic, but with the U-boat losses there already high this year, and with more effective Allied air and sea cover, he may now look to the South Atlantic for easier pickings. My assessment is that we should do what we can to save this convoy.”

“What do we know about U-515?” Fan said.

The officer pushed up his glasses again and peered at his notes. “Kapitänleutnant Werner Henke. An exceptionally capable solo commander who sank nine ships during his first patrol last year. He has already sunk two ships in his present patrol, the British California Star off the Azores and the French Bamako off northern Senegal. If you were to choose a commander to seek out and hit a convoy on his own, he’d be your man.”

“What are our assets in the area?”

“TS-37 has a weak escort, only one corvette and three armed trawlers. That’s pretty standard for West Africa convoys at present, with the best ships and captains needed in the North Atlantic. There are two long-range Hudsons of RAF Coastal Command based at Freetown, and the convoy commodore could also call on the US escort carrier USS Guadalcanal with its Wildcats and Avengers. But Guadalcanal is currently in the mid-Atlantic, too far off to provide any kind of air cover, and barely within range for a reactive strike. By the time the aircraft arrived, the U-boat would be long gone. And none of those aircraft are specialized sub hunters.”

Bermonsey glanced at the clock again, and then at Fan. She noticed how pale and tired he looked. “Turley? Your assessment?”

“Sir.” Fan took the two convoy files from the officers opposite, one for ONS-5 in the North Atlantic and one for TS-37 off Sierra Leone, and marshalled her thoughts. She opened the files and put the diagrams showing the two convoy orders of sailing in front of her, rows and columns of ships, more than sixty of them in all. That meant perhaps eight thousand crew altogether, many of them with wives and children waking up this morning wondering where they were, with no idea of the machinations being played out that might see them through this day or condemn them to a terrible death. She quickly rehearsed in her mind what she intended to say, and then cleared her throat.

“One possibility is inaction on both convoys,” she said. “We know that assault convoys are currently in preparation in the Clyde for imminent seaborne landings in the Mediterranean, at a destination that’s still top secret. Any Ultra intercepts related to U-boats potentially targeting those convoys will absolutely have to be acted upon, all of them. Given that, it would be disastrous if by acting on an Ultra intercept now we finally take that one step too far, pushing someone in B-Dienst to realize that we’ve cracked the Enigma code and to change it just before the assault convoys sail. The destruction of one of those convoys could set back the war incalculably.”

One of the two code breakers in the room, an Oxford mathematician named Johnson, pushed his chair back and put his feet up on the table, taking a pipe out of his pocket. “Yes, that’s possible, but by deliberately not acting you also create a pattern, don’t you? If I were a clever analyst in B-Dienst I might notice a welcome but strange increase in the success rate of U-boat contacts with convoys, and I might then be persuaded to look back over the preceding months and begin to suspect that something was not quite right. Do you see what I mean? Inaction means not only do we do nothing to save those convoys, but we might also compromise Ultra completely. That might be their key to realizing that we’d broken the code. If I were that analyst, having decided that Enigma had been broken, I might wonder why the intercepts were no longer being acted on. I might then begin to suspect that we were protecting our intelligence coup because something big was in the offing, something like a seaborne invasion.”

He glanced at the other code breaker, who nodded in agreement, then put his pipe in his mouth, folding his arms and giving Fan a stolid look. She turned from him and addressed Bermonsey. “I agree. That was going to be my next point. That’s why I recommend that we do take action, and redirect TS-37.”

She sat back, feeling slightly sick as she always did having chosen one convoy over another, trying not to look at the sailing order for the doomed ONS-5. Bermonsey leaned over and pushed the TS-37 file toward the two code breakers in case either of them wanted to view it. “Does everyone agree? Good.” Fan picked up the ONS-5 file, and Bermonsey addressed the table. “Let me tell you where we are today. In March we lost a hundred and twenty merchant ships, for twelve U-boats sunk. In April so far it’s been sixty-four ships for fifteen U-boats. Are we turning the tide? The Admiralty thinks so. They think this coming month will be the crunch. But we have to keep our nerve, now more than ever. Any chink in our armor, anything that lets the Germans suspect that we’re on to them, and we’re all sunk. Right, everyone. Back to the next set of decrypts. Johnson, that second file, if you please.”

Johnson tapped his pipe on the table, catching everyone’s attention. “Come on, Bermonsey. What’s it like?”

Bermonsey stared at him. “What do you mean?”

“You’re the only one here who’s actually done it. Stood behind a periscope. Had a ship in your sights. Given the order. Watched men you’ve condemned die in the sea.”

Bermonsey gave him a cold look. “It’s called war. You kill the enemy.”

Johnson waved his pipe at the file Fan was holding. “What about when it’s not the enemy? What about when a submarine captain has to look through a periscope and murder his own side? How would that feel?”

Bermonsey glared at him. “Keep your mouth shut, Johnson,” he snapped. “Now pass me that file.”

Johnson leaned sideways, his feet still on the desk, sifted the papers, and picked up the file. “I’m not one of your sailors, Bermonsey. You can’t order me around.”

There was a sudden tension in the room. Fan saw Bermonsey look at Captain Pullen, who had heard the exchange. “Johnson, a word,” Pullen said. Johnson sighed theatrically, tossed the file in front of Fan, pocketed his pipe, swung his legs off the desk, and walked out of the room behind the officer.

They all knew what “a word” meant. Ever since Turing had broken Enigma, there had been the problem of what to do with his team of code breakers. Some had remained poised for the next decryption, ready in case the Germans altered the machines as they had done with the naval Enigma in early 1942, leaving Bletchley in the dark for almost a year. Others had been reassigned to work on the Colossus computer and Lorenz, the German High Command code. A few of the less socially awkward ones had been flown off to America to teach at the US code-breaker school. Others had been moved to the special operations hut and naval intelligence to help with the cat-and-mouse game they were now playing, using the decrypted intercepts to swing the Battle of the Atlantic in the Allies’ favor. Some, like Turing himself, had taken to it well; a few had decided that their talents were being wasted. They were all under pressure and occasionally the pot bubbled over. One thing was for certain: they would not see Johnson in this hut again.

Bermonsey reached over, picked up the file and nodded at Fan. As she followed him to the office at the end of the room, her mind was racing. She thought about what Johnson had just said: when it’s not the enemy. What could he possibly have meant?

5

Fan followed Commander Bermonsey into the office and closed the door behind them. Through the window she could see others huddled in their coats hurrying up the path toward the mansion and the bombe huts, the result of the second early-morning train having arrived at Bletchley. She shut the blind and turned to the table in the center of the room. She was carrying the file for the mid-Atlantic convoy, ONS-5, and Bermonsey had the one for convoy TS-37 that had been the subject of the altercation with Johnson. She put hers on the table beside his, and opened them both up. Two files: one meant life for the crews, the one that would be left open; the other might mean death. The conference in the operations room had already decided which file would be shut and which left open, but allowing a final reflection in this room as the clock ticked down to the phone call had become part of Bermonsey’s routine. He stayed standing, leaning on the table and inspecting the files as he always did, staring at the top pages with the convoy orders of sailing. To Fan it seemed as if he were at sea again, a captain addressing the ships’ companies, telling the crews in both convoys that he was not judging their qualities as men but was making a decision based solely on the calculus of war.

She glanced at the clock. Ten minutes to seven. At 7:15 on the dot, Bermonsey would pick up the phone and call the rear admiral commanding the Naval Intelligence Division of the Admiralty’s Operational Intelligence Center in London; minutes later the order would be issued to reroute one of the convoys. What those at sea did not know, could never know, was the existence of Ultra intercepts that were not acted on, the files that were closed in this room and sent to storage stamped Top Secret, the result of decisions known only to those in the special operations hut, who were under strict instructions not to put down any of their analysis on paper and were sworn to secrecy for life. Fan had been present when Churchill himself had visited the hut and told them that nothing was more important than securing the Atlantic supply line, that the decisions made here could win or lose the war. Nothing could leak out; nothing could be left to chance.

She watched Bermonsey leaf methodically through the contents of the files — the convoy route plans, the cargo manifests, the secret Admiralty orders to the convoy commodores and escort captains — as if he were registering but not reading them, doing little more than glancing at the headings to make sure that everything was in order. She waited while he stood back, and then she plucked up courage and asked him the question that had been burning in her mind. “What did Johnson mean, sir? Not the enemy?”

He stared at her, and for a moment she thought he would snap at her, too. Then he took out a cigarette, tapped it on the table, lit it and drew in deeply, holding the smoke in and then exhaling upward so that it wreathed the single bare bulb that hung above them. He closed his eyes for a moment, then looked down at her again. “You shouldn’t ask questions, Fan, even in this holy of holies. You know that.”

“Johnson knew that too, sir. He’s wanted out ever since being posted here. He’s been badgering Pullen about it for weeks.”

“I know. Not calculated to raise my sympathy.”

“Sir.”

He took another deep drag, and exhaled forcibly. “Even so, I should have thanked him for his opinion. I shouldn’t have snapped at him. We owe those men everything.”

“They’re the genius code breakers, but we girls do this job in operational intelligence at least as well as the men. We’re as clever at math as they are, but because academia is a man’s world and nobody gave us the professorships and fellowships, we’re not used to having elevated opinions of ourselves. It means we’re tougher than they are, more used to taking knocks. Put a man like Johnson in this room where the life-and-death decisions are made, and he’d probably go to pieces.”

Fan felt her face flush. She had never spoken to him like this before. He gave her a wry smile, took another deep drag and then carefully pressed the half-finished cigarette into the ashtray, putting it out. His look hardened. “You asked a question, and I owe you an answer because of what you’re about to be drawn into. What I’m going to tell you now is beyond top secret. I mean, beyond ultra top secret.”

“Sir.”

He glanced at the clock, and then pointed at the mauve-and-red ribbon on the left breast of his uniform jacket. “You know what this is?”

“The Distinguished Service Order.”

“I got that after my third patrol out of Malta, in August 1941. We’d shadowed a small Axis convoy out of Benghazi heading north, and we finally got into position in rough seas off eastern Sicily. I put three torpedoes into the largest ship, a converted liner. I knew it was a troopship, but it turned out to be carrying walking wounded back to Italy for convalescence. Two thousand men went into the water, and maybe two hundred were picked up by the escorts.”

Fan looked at him. “Walking wounded return to fight another day. You were saving Allied lives.”

He pursed his lips, staring at the files on the desk. “War is never black and white, even this one. The virtue of destroying an enemy like Hitler or Mussolini is not in question, but it’s what we have to do to get there.”

“I can see why Johnson’s question hit a raw nerve.”

“It wasn’t so much that. I was thinking of the decision I’m about to make now.”

“My assessment remains the same. We save TS-37.”

He reached over and closed both files. “I’m not asking for your opinion any more.”

She stared at the closed covers, dumbfounded. “Sir?”

“We’re not saving any convoys today.”

She felt an icy grip in the pit of her stomach. “I don’t understand.”

“I’m afraid our convoy conference was something of a sham. I had to make it seem as if it were normal procedure, right down to entering this room with you as usual. We decided to bring you on board some time ago. Do you remember Churchill’s visit last month?”

“Of course. You and Captain Pullen were holed up in this room with him for hours. We could smell the cigar smoke for days afterward.”

“Pullen is one of very few others at Bletchley who are party to what I’m about to tell you. Very few. Do you remember Churchill speaking to you in the hut afterward?”

“I was flattered. He only talked to a few of us, and he chose me.”

“It wasn’t random. After Pullen and I recommended you, he wanted to check you out himself.”

“You recommended me? For what?”

He picked up the half-finished cigarette from the ashtray, pinched off the burned end and relit it. He took a deep drag, holding it in for a few moments, then stubbed out the remainder. “One useful aspect of the conference is that it gave you an up-to-the-minute picture of the air and sea assets off West Africa. Well, there’s another asset, and it’s top secret. One of our own submarines is in position off Sierra Leone.”

“In position, sir? Is she a U-boat hunter?”

“She’s one of four specialized long-range boats Churchill ordered constructed early last year, soon after the Japanese war began. With the sea war in the Mediterranean swinging firmly in our favor, we took four of the best surviving captains and crews from the Malta and Gibraltar flotillas to man the new submarines. Officially they were men who had stacked up the requisite number of patrols for shore deployment or were being stood down through stress or illness, but in reality they were all reassigned to a top-secret operation. Two months ago we added four American boats to the flotilla, crewed by men with extensive operational experience in the Pacific. It’s no coincidence that I’m a submariner too. My assignment to Bletchley late last year was part of this operation. Churchill also vetted me personally.”

Fan was struggling to understand. “Why after the Japanese war began? Why is that significant? What have the Japanese got to do with this?”

Bermonsey pulled out another cigarette and tapped it on the table, but left it unlit. He glanced at the door and spoke urgently, his voice lowered. “Four days ago in the Indian Ocean off Mozambique, U-180 rendezvoused with the Japanese submarine I-29. We know about it because a sharp-eyed girl in the bombe cribbing hut spotted an Ultra decrypt about to go on the slush pile with an apparently unintelligible word that she realized was Japanese. The word was Yanagi, meaning Willow. It’s the Japanese code name for submarine missions to exchange technology with Nazi Germany.”

“I remember another Japanese sub, I-30,” Fan said. “Last August, wasn’t it? Lord Haw Haw in the Nazi radio broadcast made a big splash about the arrival of the submarine at the U-boat base at Lorient, having avoided Allied detection.”

Bermonsey nodded. “That was during our dark period, while we were unable to penetrate the new naval Enigma. A really bad time for us; worse for the men at sea. Ever since the Axis Powers’ Tripartite Pact in September 1940, Bletchley has been tasked to look out for anything indicating missions like that of I-30. We had no way of detecting that one, but since cracking the naval code again early this year, we’ve been keeping an eagle eye out. The decrypt on the twenty-sixth was the first indication we’ve had of another exchange, though by then of course it was too late to do anything about it.”

“What were they exchanging?”

“In the case of I-30 last year, it was high-value raw materials and design technology. The Japanese sent mica and shellac, and the blueprints for an aerial torpedo; in return, the Germans sent industrial diamonds, an example of the Würzburg air defense radar, a Zeiss artillery fire director, sonar countermeasure rounds, that kind of thing. Fortunately, most of the return cargo, including the blueprints, were destroyed when the sub struck one of our mines off Singapore. In the case of U-180 and I-29, it’s different, even more worrying. After we identified the Ultra decrypt, our intelligence networks have been working overtime to establish what might have been exchanged. It now seems certain that a passenger on board U-180 was the Indian nationalist leader Subhas Chandra Bose, who has been in Berlin being sweet-talked about how the Nazis would support him should the movement rise against the British in India. His transfer to Japan is a concern, because once there he might be sent to Burma and coerce more Indian Army sepoys to go over to the Japanese and the so-called Indian National Army. But of even greater concern, particularly to Churchill, was what I-29 was bringing in exchange. Our agents in Penang report that her main cargo was more than two tons of gold.”

“Two tons of gold,” Fan breathed. “To buy what?”

“That’s exactly what worried us. What worried Churchill. We always knew that the German High Command might use the naval Enigma for purposes other than basic U-boat movement orders. Ever since the Japanese entered the war sixteen months ago, we’ve been keeping an eagle eye out for intercepts that might suggest covert supply arrangements between them and the Germans. The Germans are running out of basic raw materials, especially low-volume, high-grade metals and compounds that might be carried in useful quantities even in a submarine, and the Japanese want materials of their own. With surface shipment being impossible because of our control of the sea lanes, long-range U-boats are the only option. About two months ago, a US naval analyst in Washington linked an Ultra intercept to reports from agents in Tokyo that a special shipment had been requested. The material was radioactive uranium. That’s the real reason why those two American officers joined us six weeks ago. They want to be here in case we catch any similar intercepts. The Americans have been involved in a top-secret project to use uranium to make some kind of catastrophic bomb, and the idea that the Germans and the Japanese might be embarked on the same kind of project has put the fear of God into everyone involved.”

“Including Churchill,” Fan said.

“Especially Churchill. When he said the war will be won or lost in the Atlantic, he wasn’t just thinking of our merchant ships. He was also thinking of what might break through our defensive screen and reach the U-boat bases at Brest and Lorient. Despite the best efforts of our ships and aircraft, it’s still feasible for a U-boat on a long-distance voyage from Japan to reach Nazi-controlled territory undetected, recharging its batteries at night and refuelling from tanker U-boats on the way. The same goes in the other direction.”

Fan stared at the files, speaking slowly. “You need me because any operation to take out these U-boats or Japanese subs would be based on Ultra intercepts, and would therefore have to be factored into the calculus that’s my speciality. Act on too many intercepts and the Germans will become suspicious. And on the day when one of these special intercepts is acted on, Ultra intelligence related to other U-boat movements would have to be ignored and no convoys saved. Days like today?”

“Correct. We knew you were the right person for the job. Quick assessments will need to be made. You’ll continue to do your routine job as part of the operational intelligence team within the hut, the job you have been doing today, but any time one of these special intercepts is detected you will also be wearing this other hat, unknown to most of the others.”

“When you said our sub was in position, you meant to intercept U-515.”

“No. I meant to intercept convoy TS-37.”

“To intercept the convoy. Now I really don’t understand.”

“A long-range U-boat is due along that coast in a few days’ time. We know this because an Ultra decrypt a week ago showed that a tanker U-boat was heading to a refuelling rendezvous far to the south of the known operational schedules of any other U-boats currently in the Atlantic, including U-515. Our sub off Sierra Leone is one of two off the West African coast hoping to intercept the long-range U-boat when further decrypts pinpoint her position. But meanwhile, something else has cropped up. One of the ships in convoy TS-37 is carrying something we do not want to fall into enemy hands. Open up the cargo manifest for Clan Macpherson.”

She shuffled through the papers in the TS-37 file and found it. “Pig iron, hemp, general cargo from India. Pig iron is presumably code for manganese. Ah. It’s penciled in at the bottom, to be picked up in Durban. A consignment of gold bullion.”

“A very big consignment. We’ve secretly shipped as much gold as we can from South Africa since the outbreak of war. We need it to build up our reserves, and to fund the resistance in Europe. A consignment of this size would also be enough for the Germans to pay the Japanese for what the Nazi scientists want above all else at the moment: a cargo of uranium ore. The Japanese have opened up a new mine and apparently have a surfeit.”

“But how could the gold possibly fall into German hands?”

“Because the German High Command has ordered U-515 not to sink Clan Macpherson, but to capture it. We know that from an Enigma intercept. Despite our best efforts to keep all gold shipments out of South Africa secret, we believe that the Nazi agents in Durban must have caught wind of this one and passed the information up the line. They’re the ones we’re bluffing by relabeling manganese as pig iron. There is a reason why we haven’t shut them down, but that’s no concern of ours for now. What we also learned after the ship had sailed is that there are Japanese-trained operatives from the Indian National Army planted among the Lascar ratings in the crew of Clan Macpherson who are there to take it over once U-515 begins attacking the convoy, and who will then cause her to fall behind so the U-boat can come alongside. If the U-boat causes enough destruction in the main body of the convoy, then that’s where the escorts will concentrate, leaving stragglers to their fate. We know it’s a weak escort, and so do the Germans. We believe that the plan is then for U-515 to rendezvous with the long-range U-boat at a secret location to transfer the gold aboard. An audacious plan, but ingenious. And we have to do anything we can to stop it. I mean, anything.”

Fan suddenly felt sick. “My God. Now I understand what Johnson was saying. Our sub is there to sink one of our own ships. To sink Clan Macpherson.”

“That’s the real reason I snapped at him. He’s one of two cryptographers we brought in on this secret and assigned to spotting the special intercepts. We’d known about the long-distance U-boat program from agents in Japan, but it was Johnson who took that decrypt spotted by the US analyst and put it alongside a number of anomalous movement orders we’d decrypted over the past few months, ones that don’t mention a U-boat by name and would normally be put in the slush pile of non-actionable intelligence. The decrypt fingered by the US analyst used a German code word for Japan known to our agents in Tokyo, and by cribbing from that Johnson was able to isolate several dozen previous communications that we realized must have been going to the long-distance U-boats. Bingo, we had the code markers to look out for future messages. It was bloody clever, really. Pity he’s turned out to be a loose cannon.”

“Alan jokingly calls Bletchley ‘the machine,’ but he says it’s really an analog of the human mind, full of untapped potential but riven by human weaknesses.”

“Turing? Well, at least we can rely on him. He’s the other cryptographer in on this operation. He can take over Johnson’s work as well. He doesn’t seem to be affected by stress.”

“He runs it off. Hundreds of miles a week. We’re all affected by stress, whether we acknowledge it or not.” She closed the file. “So what do we do about convoy TS-37?”

Bermonsey tapped the cigarette again. “Officially, you and I came into this office to make the call to order that convoy to be rerouted, and as far as the rest of this hut is concerned, that’s what we’ve done. When they see tomorrow that the convoy has been hit, it won’t be the first time that’s happened. For every redirected convoy that makes it away in time, there are others that are just too sluggish. And there are U-boat captains who go maverick, changing course without sending signals that we might intercept. In normal circumstances, Werner Henke in U-515 is just that sort of captain. I know; I was one myself. In this instance, though, with his special assignment, we can be sure that he will stay on course. With the focus in the hut on the big convoy battle that everyone now expects in the North Atlantic, one that we have helped to set up today, the loss of a few ships off Sierra Leone will soon be history, even with their precious manganese ore. That’s the brutal truth of it.”

She gestured at the phone. “So what do you do now?”

“Anything that comes out of Bletchley on this line is immediately acted upon. Those were the Prime Minister’s orders, and this is no exception. The rear admiral commanding the Operational Intelligence Center is another in our group, and as soon as he hears the code word we have agreed for this operation he will act on it, sending the order to our sub. To others at the OIC it will appear to be another Bletchley directive, unusual but in no way betraying what is actually being ordered. By leaving the route of TS-37 unchanged, we can predict that U-515 on its present course will make contact with the convoy at about 2300 GMT this evening. At that point our submarine will already be shadowing the convoy. Her orders will be to sink Clan Macpherson soon after the convoy is hit, to make it seem as if it is another U-boat attack.”

“It has to be the ship?”

Bermonsey nodded grimly. “We can’t afford to send our sub after the U-boat. That could be a game of cat-and-mouse that we might lose. We’ve thought of every other possible scenario, and there’s just too much that could go wrong. We could order the sub to wait until the U-boat surfaces beside Clan Macpherson, the only time it would be exposed and vulnerable, but by attempting to take it out that way, the chances are we’d put a torpedo into Clan Macpherson as well. If there were a fight and our sub were forced to the surface, then the whole game would be up, everything we have worked on to try to undermine the gold and uranium trade. The Germans would instantly realize that we’d been on to them, and change Enigma. You know how disastrous that would be. The sub simply cannot allow her presence to be known, either to the escort or to U-515. To Henke it must simply appear that another U-boat was in the vicinity, a maverick captain like himself who was keeping radio silence. The convoy commodore and the escorts will know nothing of any of this, and nobody outside our group here or in the OIC will know that my message was an order not for the convoy to be rerouted but for one of our own subs to sink one of our own merchant ships.”

“What about our submarine captain? He’s going to be ordered to do the unthinkable.”

“We vetted those crews for a reason. They know they’re a top-secret outfit, under the direct command of Churchill. For them, that will be enough. They’re hardened killers. They’ve all had to do what I’ve had to do, watched men screaming and burning in the water through the periscope, men you have put there. When you see that, they’re no longer the enemy, just men. I know he’ll do it because I know I would do it.”

He stood up, straightened his uniform and went to the phone. Fan tried to focus, but her mind was in turmoil. The layers of secrecy suddenly seemed like a hall of mirrors, trapping her inside, leaving her uncertain whether she was looking at illusion or reality. In truth, she had little idea what all the others really did here, that silent shivering army who marched in every morning with her from the train, exchanging quick pleasantries over that first welcome mug of tea, then disappearing into huts all over Bletchley with sentries at the doors. For all she knew, her friend Louise could be part of some other top-secret enterprise. She could not even know how far Bermonsey had let her in, whether he had told her the full story. The need to prevent the Germans from getting gold that could pay for uranium was clear enough. But was that really enough justification for sinking a British ship? Was there something else going on, something on that ship other than the gold?

She looked at him standing by the phone, counting down the seconds on his watch. His eyes had hardened again, and she knew that she was not going to get anything more out of him. He had told her what she needed to know to do her job, and that would be it. That was the way Bletchley worked.

One minute to go. She forced herself to think of the Atlantic again, of the ships battling the spray and the swell. It would still be dark, the end of the dog watch. Exhausted men would be falling instantly asleep in their bunks, fully clothed in case they had to spring into lifeboats; bleary-eyed men would be replacing them, clutching cups of cocoa and staring at the dark smudge of the ship in the line ahead, men barely in control of the cold and the fear. Normally it was an image that gave her some comfort, knowing that one file had been kept open, one convoy given a chance. This time it was different. This time, she would be saving nobody.

Bermonsey lifted the phone off the receiver. It was answered instantly. He turned away from her, speaking urgently. “This is Bletchley. Code name Ark. I repeat, Ark. Execute.”