The River of Diamonds

16

It was common Gestapo torture to take a man out of boiling water, and plunge him in ice up to his neck. But our next three days were every bit as excruciating. The blaze of the sun was too much for our ebbing strength and our treks were made at night. The nightmare became more substantial as the light waned insubstantial; there were times when I wavered between a detached, somnambulistic stumble through the red-hot grieshoch of sand and an uncaring delirium. I threw away the compass, steering only at the twin spitskoppe peaks of Uri-Hauchab, bullet-shaped, scored like a dumdum bullet. They would fade to invisibility in the blackness before moon-rise, — when they did become visible I was unsure whether their wavering, uncertain outline was not a mirage. On two occasions we jerked from our stunned sleep to find our water-bottles full and a row of tracks running into the dunes, but there were no more notes from Shelborne. Koeltas saw his plan clearly, too, but we had no strength to stand sentry. He fired once at the unaccountable helio of light, but Shelborne was out of range and the clap of the shot fell sick against the sound-absorbing sand.

I woke. The sun stabbed my eyelids. The hills were absurd. Some were upside down and their sides leaned over impossible overhangs. The twin spitskoppe of Uri-Hauchab, at whose foot we had camped in exhausted triumph the night before, hung suspended from the sky like the teats of a monster cow. The flanking ridges, chopped into light and shadow waves by last night's moon, this morning were built up of globes and plates alternately: here and there others rose like inverted mushrooms. The edges were shimmering, ill-defined, and the lines which the moon had carved so firmly were evanescent, fragmentary. My weak laugh was lost, — I knew that I was at the end of the line. I raised my fist and screamed an obscenity towards the dunes. Shelborne! He had prolonged our agony with his canteens of water. Shelborne! Christ! How he must have enjoyed killing Caldwell! Now, thirty and more years after, he'd pulled the same killer-gag on the next person to try to find his secret! I rose to my knees. The whole sky and landscape reeled, turned upside down, stood out clear. Not death, but a mirage. A few hundred yards ahead was a rough cairn of stones. The Namib, in all its wild contortions, hadn't invented that. It was man-made. Those stones had been placed in position.

I shook Koeltas to make sure I was not imagining it. He stirred, but lay still. With some frenetic last reserve of strength, I hauled him up so that he faced it.

His eyes went wide. 'Hadje Aibeep!' he click-clacked. 'On my mother's grave, Hadje Aibeep!'

Then the whole scene spun, altered, reversed — the mirage spun its wild patterns again before our eyes.

'What is it?' My lips were rubbery, congealed. 'What is Hadje Aibeep, for God's sake?'

He shook himself like a dog. 'I never thought to see it. The cave of Hadje Aibeep — the little wild men of the desert throw their dead into it. Each puts a stone above for a dead man. The cave is deep. They say there is a lake at Hadje Aibeep, under the desert. Let us look.'

We stumbled to the cairn. Next to it a deep shaft went down into the bowels of the earth. The hole was circular, about twenty feet across. Its lips, for about ten feet all round, were smooth, polished, of a substance I could not identify — not volcanic lava but some strange sort of solidified mud from the depths below.

We could smell water. I dropped a stone, and from far below came an answering splash.

This was the ancient river; this was the bearer of diamonds!

We had to get to the water, but we had neither rope nor strength. Somehow we would have to negotiate the smooth incline, up which the air came pure and sweet. I took a rock to the geyser-like mud. If we couldn't cut steps, we might as well be out in the parched dunes. I hacked at it; my crude tool sank easily: it was as soft as soapstone.

'I want something sharp,' I told Koeltas. 'I'll cut the first lot of steps and you the next — in turns.'

He held up the water-bottle. 'We drink all this first, eh?'

'Yes.' If we couldn't reach the water below, we'd die anyway. We finished it. I went to the cairn for a sharp stone.

'No!' said Koeltas. 'Not those stones — bad luck. Each stone is a dead man.'

At the base, half-covered by sand, were the remains of Bushmen arrows — the shafts had gone but the flint-heads remained — thongs of bows, primitive stone-head axes and crumbled wooden shafts. Bushmen buried weapons with the dead. I found one axe with about a foot of shaft, and the thongs lashing it to the head looked fair.

The first few steps were the worst. Once I could fashion a grip for my hands, however, the work went quickly. It was mercifully cool and the smell of water was tantalizing. Although it grew darker, there was some suffused light deeper down. After I had chipped foot- and hand-holds for about fifty feet, I sent Koeltas down for his stint. I lay in the shadow of the cairn.

Among the savage gramadullas I thought I saw a helio of light. Shelborne was watching us.

I cut the final steps. Down, down, down. Then I saw: below me was water — swift, flowing, with chocolate reflections as from polished steel. The shaft was through the roof of an immense cavern. A beach of pure white sand would cushion my drop of the last twenty feet. I shouted to Koeltas to come, then let go and fell.

I lay still, spellbound by the muted loveliness of the scene after the torture of the dunes. We were in a huge cavern to whose dim roof soared enormous pillars of limestone, intercalated with hundreds of pure white stalactites. We lay and cupped the water to our mouths. I estimated the river to be half a mile wide; it may have been more. The white beach was littered with Bushmen bones and skulls, and ran along the water's edge into the distance.

Koeltas anticipated my thoughts. 'It flows to the sea! To Mercury!'

My hunch had been correct: here was the old river which had once flowed in the bed, now dry above, and had been forced into this subterranean channel by the uplift of the coastline. Here was the diamond-carrying river, the distributor of the fountainhead's riches! The fountainhead itself must lie between Hadje Aibeep and Mercury. There was nothing ancient, however, in the strong young flow of the river. The brown told me, this is floodwater. Was it on its way to burst through to the sea like the Orange at Oranjemund? There was no mouth in Spencer Bay; the outlet must also hold the secret of the fountainhead. We must follow the river, here where we could see.

Our march was cool and easy after the aridity of the dunes. The sand fringe was pebbly and comforted our blistered feet. We rejoiced in the smell of water. The shaft of Hadje Aibeep illuminated the first part of our way. Then Koeltas grew uneasy about the dark, but it seemed obvious that the line of what I had thought to be blowholes must be vents similar to Hadje Aibeep, though smaller. I had not expected them earlier than Strandloper's Water, but there were some at irregular intervals. Above, they must lie among the wasteland of rocky outcrops we had avoided, which would account for our not having seen them.

By nightfall — the cavern became pitch-back as the sun sank — I estimated that we must be half-way back to the coast. Before rolling in my sleeping-bag, I went to the water's edge. The water had ceased its rapid flow and was sullen, turgid, scarcely moving. What mammoth obstruction lay ahead to dam it up? It also seemed the the cavern's roof was lower — was the water-level rising towards the ceiling? The quantity pouring in would trap us if there were no exit, and the occasional vent was far out of our reach. To climb the stalactites would be as impossible as to scale a skyscraper. Was Shelborne's killer in front? Or behind?

By mid-morning next day we passed, according to ray dead-reckoning, directly under Strandloper's Water. The roof was lower and the water, so friendly the previous day, was menacing. The river beach had disappeared about Strandloper's Water and now we picked our way cautiously along water-smooth rock within a couple of feet of the river itself. Ahead — maybe half a mile — I saw a shaft of sunlight. I made up my mind.

'Koeltas,' I said, 'if that next blowhole is close enough to our heads, let's get out of here.'

He shuddered and nodded. As the ceiling had crept nearer our head, he had become more strained. From time to time he looked back, holding the rifle.

We were in the sunshaft of the blowhole. I hauled Koeltas on to my shoulder, but it was still out of reach. The smooth rock offered no hand-holds. We would have to go on. What had killed the springbok at these blowholes?

The going worsened and we found ourselves clinging in places to the wall and splashing in the water. Ahead, another shaft cut into the blackness. I edged forward. My head touched the roof. A thrill of panic ran through me, blind, unreasoning fear. Where in God's name were we? We were trapped like rats in a sewer. Now was the time for Shelborne to make his kill. The water was deep, marginless, on my right. What if we emerged in the quicksands? We would simply be exchanging one form of dying for another. We must get out!

The thunder of the crash stunned me — heavy, sudden, like a broadside from ahead, an ear-deadening, diaphragm-ripping bolt of sound.

The Bells of St Mary's!

Cringing on the rocky shelf, there was no barrier of sea or Mercury or rockroof to cushion us: we were in the combustion chamber of the Bells.

I grabbed wildly. My grip went into Koeltas's thin shoulder. His slitted eyes were wide with terror, I opened my mouth, but I could not hear my voice. We must get out, get out quick, if we wanted to live.

I gestured forward to the blowhole. We tore, scrabbled, fought our way, ripping our clothes, bruising our knees and palms, tearing our fingernails. Half-way to it the water rose, rose, rose. I abandoned the rock and swam, striking out desperately. My knuckles struck the rock-roof as I flailed. My kick grated against the steel of the Remington — Koeltas swam with it slung. Half a dozen strokes to go. Then I saw.

The turgid chocolate surface, mocking a surfacing U-boat, swelled like the sea-bed off Mercury.

Gas!

My brain registered while my body fought — in slow-motion it seemed — for the opening.

Diamonds… blowholes… gas!

I lived again, in mental photoplay, a scene years before: the same dark tunnel, the black roof, the vent. Jagersfontein, one of the big old diamond mines not far from Kimberley. There had been a fissure in the rock — but it had burned. And it had burned for thirty years, they told me.

Burning gas was methane gas — killer-gas!

Methane gas — not the harmless rotten cabbage gas whose bubbles I had seen on the sea-bed — was bursting through the swollen river. The oxygenless sea was quite a separate phenomenon from that in front of me now. The solution to the whole complex problem fell into place. There were, in fact, two gases: one which I had found on the sea-bed which was fatal to fish and harmless to humans, and the second which was fatal to everything. Methane had killed the great herd of springbok, forcing its way through blowholes and smaller fissures where they scented the underground water. The harmless gas was found only at sea, but the killer-gas was present on the land and on Mercury. That was the Bells! — methane, alias the Bells! The Bells were not regular but intermittent since it required a build-up of pressure for the gas to burst out. Another great piece of the jigsaw had fallen into place.

Instead of a barrier of sandbars, like Oranjemund, I knew now that the ancient river now in flood was held back from the sea not by sandbars but by pressure of methane gas. The whole coastline and bay under Mercury must be a gigantic cupola-shaped underground cavern, of which the Glory Hole was a small exit. The cupola, shaped like an inverted steel helmet, was filled with methane gas. The river flooded and debouched, into the domed undersea cavern — the diamond fountain-head itself! Enormous pressure built up as millions of gallons of water compressed millions of cubic yards of methane gas. More water poured in; more gas was accumulated. Pressure built up and up. The rockroof under Mercury took a strain like a hydrogen balloon in the stratosphere, hundreds of pounds to the square inch. The roof trembled under the great pressure — and Mercury shook. It took years for the Orange River floods to work up sufficient pressure to break the sand barrier; it would take this underground river as many years to do the same to Mercury. When the Oranjemund sandbars burst, they said, you could hear the noise for more than a hundred miles out to sea. A British warship during the war had cleared for action, thinking the Orange's breakthrough was gunfire.

The mystery of Gruppe Eisbar's end became clear in my mind now. The wolf-pack had dived into the Glory Hole at a time when the gas was still building up. Therefore the air inside the Glory Hole was pure when the captains rowed themselves ashore to the graveyard in their rubber dinghies. Shelborne must have known there was a methane fissure under the graveyard toolshed and with brilliant opportunism had induced the captains to stay there and close the door. Then pressure had built up, the gas flooding into the Glory Hole beneath and the toolshed above, destroying Gruppe Eisbar and the captains. 'The 'fauler Zauber' must have been, as I had surmised, the incoherencies of the dying radio operator.

The key, I realized, was the intermittent nature of the Bells — the balance between gas and flood build-up. Shelborne had learned the secret and knew when to get out — for example, the night we had seen him from the Malgas fleeing to Sudhuk. The Glory Hole faced into the prevailing wind and Mercury was relatively safe while the south-western ventilated it; the island could become fatal when it was calm. My dive and discovery of the oxygenless sea and harmless gas had merely bedevilled the whole thing.

What a fool I had been over the Mazy Zed's last mining operation, confusing the real killer and the innocent sea-bed gas! It was at my suggestion that the pumps had been laid right into the death-mouth of the Glory Hole, and they had filled the 'tween-decks with the swift, near-odourless killer before the men knew what was happening. I remembered how I had heard the Bells strongly before we went ashore. Out in the open, the deck hands had escaped, as indeed we had on the island where the wind blew the gas away. Shelborne had made his threat to annihilate the crew in the knowledge that the Mazy Zed's powerful pumps would suck up the methane. And Bob Sheriff had died by running into a big pocket as he went past the open-grained quicksands in his boat.

I felt myself being lifted into the vent. If the methane pocket under me beat me to it… I'd rise out of the cavern all right — I'd rise as a dead man. The quicker I got out, the more chance Koeltas would have. My fingers clutched frantically at the water-worn rock. I found a hold, fought, slipped, swung myself clear of the water. It didn't seem more than about a dozen feet to the surface, and it was three across. Higher, it was too smooth for holds. I had the only one. Koeltas splashed in terror. The rifle! I reached past his fear-struck face and wrenched it free, jamming its butt to one wall, barrel to the other. He snatched the sling and hung on, half-in, half-out the water. There as only one way of getting up. I threw my body backward, smashing with a bone-jarring jolt, into the back wall. Feet clamped against the opposite wall, I levered and jerked myself upwards in a skin-ripping series of convulsions. Koeltas followed. I reached ground level and shot out backwards, like a fish out of a seine net, on to the soft sand. Within seconds, Koeltas was there, still clutching his rifle. I jumped to my feet, half-blind in the searing sun, and ran from the death at our heels. Fifty, one hundred yards. Then I was up to my waist.

The blowhole was on the fringe of the quicksands.

My eyes, adapted bat-like to the darkness of the cavern, began to focus properly in the bright light.

I shouted to Koeltas blundering towards me. 'The rifle — pull me out with the strap!'

We had emerged on the high north-eastern shoulder of the Long Wall, next to the quicksands. If the Bells started in earnest, it would be fatal to stay — the pocket from which we had fled was small and must have dissipated itself harmlessly in the open. The soft sand trembled under me. The quicksands, the river-bed and the shoreline would soon be a death-trap. Our only route was down the Long Wall.

I grabbed the gunstrap and Koeltas eased me out of the sand's lethal hold.

The Long Wall! A narrow ledge, about three feet wide, followed the loose contour of the cliff. Koeltas and I edged towards it, fearful to start a landslide which would hurl us on to the rocks hundreds of feet below. A helio of light came from the far side of the quicksands, it was Shelborne! There was no mistaking the tall figure. He seemed to have a large pack on his back. It wasn't the pack I was interested in, however — in his hand was a heavy revolver which was not the Borchardt. Well, if he wanted to shoot it out, he'd get more than he bargained for.

'Give me the gun!' I ordered Koeltas.

'No — I shoot the bastard.'

My anger ignited against the hurrying figure. How many dead lay at his door! The methane had beaten him, so he had chosen to sit on the fountainhead, the richest poor man in the world, unable to do a thing about it himself and passionately refusing to let anyone else.

'Give me the gun!'

I took the weapon and worked the bolt to see it was running free. With infinite care, our bodies and faces clamped against the sand incline, we inched down towards the path. We had reached within feet of it when a bullet dug into the sand within a foot of my arm. The report was simultaneous. I glanced up: Shelborne lay peering at us, fiddling with the revolver for the next shot — perhaps it was jammed with sand. I could not unstrap the Remington to fire. It was a poor shot to miss me at that range. He seemed to be doing something to the barrel. Already he had had time to pick me off with a couple of snapshots before I reached the path and the safety of its overhang.

I let go and slid blindly. My tattered veldskoens bit on the harder path. For a moment I thought the weight of the rifle would overbalance me to certain death far below. I teetered, regained balance, and slipped to safety, unslinging the rifle to cover Koeltas. The Tartar-faced. skipper was right behind me, however. We ran crouched along the ledge until we had put the shoulder of the Long Wall between ourselves and Shelborne. We paused, gasping. The whole pathway seemed to sway nauseatingly.

'Jesus!' exclaimed Koeltas. 'Even here, the bladdy country shakes!'

The Long Wall gave vertiginously. It may not have been more than an inch or two, but it seemed like a malign force trying to shake us off. Talk softly! A loud sound would bring down the blancmange-like cliff on top of us.

'Come!' I whispered.

We eased along the ledge until it began to curve sharply inwards.

Koeltas held up a hand. 'He follows!'

Shelborne knew the Long Wall and it would be easy for him, once we had turned the shoulder facing Sudhuk, to pick us off on the one-thousand-foot incline to the beach. I wasn't going to give him the chance. Ahead was a buttress: I'd wait for Shelborne there — with the Remington.

We slipped round the corner: here the ledge widened into a shallow embankment about ten feet wide and fifty long. I lay down and set my sights at maximum depression. I worked the bolt and reloaded. There would be no mistake. I cuddled the butt against my shoulder.

Shelborne's speed caught me. I had expected a stealthy approach with a snapshot, but he whipped round the corner at a half-run, crouching low. He swung in under my sights. Before I could drop them I felt the heavy slug burn into my shoulder, close against the neck. As I half-rose in agony, I could not help admiring his superb shooting. His momentum had carried him round the corner, but he was already starting to back away to safety as I lifted the gun. The needle of the foresight rested in the middle of his chest, hard and clear against the black sealskin.

Koeltas was at my side. 'Skiet — shoot!' he sobbed. 'You've got the bastard — skiet!'

My eyes blurred and my finger would not come hard against the trigger. Take it easy, I told myself, you've got time and he's a perfect target. My left shoulder and neck were red-hot agony. I blinked my eyes to clear them. The elbow of my left arm, steadying the gun, felt weak. The muscle slackened. My mind was stunned, yawing with the pain. I could feel the blood running down inside my shirt. Why in God's name doesn't he shoot again? The thought drummed through my mind. He knows, blast him, he knows it was a killing shot and he won't have to waste another; I won't have the strength before I die to pull the trigger. He stood, the heavy black pistol hanging loosely by his side, smiling, upright, unafraid.

Slowly, my teeth clamped against my torn lips, I yanked the barrel up until the sights lay again on his chest. My eyelids were as heavy as the rifle. My thumb was numb against the butt but I fought for leverage with it — and my index finger responded. They tautened for the shot.

'Don't shoot! Don't shoot!'

Mary half-stumbled, half-fell across my back, knocking me forwards from my kneeling position. The rifle flew out of my hands. I heard Koeltas's savage oath and the roar of the shot and Mary's stifled scream. Shelborne spun round, cannoning into the wall. My senses were fading.

Shelborne's two shots were so quick that they sounded like one. I heard the ugly thud of the bullets into Koeltas and his thin scream of pain. He came upright and tripped over me, fell. His body jerked to the path-edge. The sand, as if extending a courtesy, fell back and he slid slowly over.

I lost consciousness.

It wasn't the land that was rocking so sickeningly, but the sea. I recognized the folding table first and then I knew where I was — in one of the Gquma's bunks. The blood-stained bandages everywhere must come from my wound. Or so I thought until I looked across at the opposite bunk. Shelborne's strong face was like lead and there was a tell-tale mound of bandages on his right side. Mary came in, took a handkerchief and wiped the ominous pink froth from his lips. His wheeze told me the rest of the story: Koeltas's bullet was in his lung.

Remembering what happened on the Long Wall brought me upright. 'Mary! What…!'

Her face was taut with worry. 'I'm glad you've come to. How do you feel?'

My mouth was dry and my head throbbed like a hangover. My hand went to my shoulder, close to the neck. There were no bandages, nothing except a small square of sticking-plaster. It was a little numb round about. I'd been shot with deadly accuracy in a fatal spot and all I had to show for it was an insignificant wound and a small ache. 'I… I…'

I was still in my Namib clothes. She hadn't even taken off the shirt. It was clear that the star patient was in the other bunk.

'What the hell goes on?' I asked harshly.

She came over so that her face was level with mine. 'Do you think you can sail this boat, John? The wind's right and we could be at Walvis Bay in three days. We've got to get him to hospital. He needs specialist attention. I've done what I can to stop the bleeding.'

'Sail to Walvis Bay?' I echoed. 'Look, Mary, my mind's still muzzy, but I do know that I was shot and that I passed out. The man who murdered your father tried to murder me. If ever anyone has blood on his hands, it's him. I…'

She smiled, and all the warmth I associated with her came flooding back to me. 'He didn't try to kill you, John.' She went to the table and picked a small sharp nylon dart-like thing out of a white surgical dish. She handed it to me. That's what he shot you with.'

I balanced it in my hand and laughed shakily. 'An anaesthetic dart?'

She nodded. 'Yes. The sort you shoot small game with to drug them for capture.'

I tossed up the tiny dart, speechless. Shelborne had deliberately aimed wide the first time — using a proper bullet — as I slid down towards the Long Wall. His delay over the second shot, which enable me to get away, was to load the dart. Clear, too, why he had stood, a wide-open target, while I battled to get my sights on him; he knew the drug would get me before I could fire. The two bullets he had fired at Koeltas were not darts, though. His superb marksmanship and guts had won that deadly exchange.

'Besides,' she said, and her eyes welled with tears, 'no man shoots his own son.'

I must be imagining her words in my drug-induced torpor, I told myself. But my head felt clearer as I swung out of the bunk. I took her by the shoulders. She sobbed quietly.

'My father! How can he be…? You mean that man is not Shelborne but Fred Tregard?'

'No,' she replied gently. 'That man in the bunk is the legend: Frederick William Caldwell.'

The tiny cabin swam around me. I held on to the table. 'You said my father. You mean… your father.'

'My father — and yours.'

'He shot me.'

'And with a bullet in his lung… I didn't know he was so bad… he half-carried you down the Long Wall to the beach and — collapsed there. I rowed you both here…'

'But Shelborne killed Caldwell.'

'He didn't, for the simple reason there was never any Shelborne. Shelborne did not exist, any more than the Hottentots' Paradise.'

'I'm not with you… He told you this…?'

She said, firmly, 'Yes, he did — on our way to Walvis. That's why he turned back after you, not to kill you as you thought, but to tell you who he was, who you are. I am his daughter and you are his son — we're half-brother and sister. He knew I was his daughter — Caldwell's daughter — in court. You saw how it took him then. He was forced — he called it his luck again — to bid against his own daughter for the sea-bed right.'

'What about the deed of cession.'

'It was a fake. He deliberately changed his handwriting to that fine italic style so it wouldn't be recognized. There was never any Shelborne. Dad was as much of a loner as you are. He invented the whole thing. He wanted the world to believe that the great Caldwell was dead.'

'And your mother too?'

'I didn't know until he told me, and she never said: before Kleinzee she had told him that if he went off on what she described as another of his hare-brained expeditions, she was through with him. She never understood his "behind the ranges" side. She wanted security, a husband with a steady job, a suburban home. Caldwell, the legend, the diamond genius — and his fate — weren't for her. She told him so. He tried to sugar the pill by saying he was off to the Hottentots' Paradise but in fact he had a hunch — like you — that Mercury was the fountainhead of the Sperrgebiet, its original and sole source of diamonds. He explored the coast and the desert. There's an enormous underground cavern…'

'I know,' I roughed in the picture of the methane gas barrier, the ancient river, and the Bells of St Mary's.

She nodded.. 'He prospected the coastline until he knew practically every rock of it. He suspected the diamonds were there. If he went back with his fountain-head theory unsubstantiated and with no diamonds to prove it, you realize what they would have said: Caldwell missed all the big ones and now he's back with one of those cock-and-bull yarns about an inaccessible treasure trove. He had to prove it. He returned to tell my mother…'

He returned?'

'Yes. She didn't believe a word of his story. She thought he'd gone off on another wild-goose chase and was soft-soaping her. He'd gone, despite her ultimatum. As far as she was concerned, he could go off for good on his wild schemes. She told him so.'

That was what sent him to the Takla Makan and the Atacama?'

'Yes. He became a sailor in order to get back to Mercury…'

'I thought that was it. The Shelborne impersonation came later?'

'It was easy. Even my mother scarcely recognized him after his blackwater fever at Strandloper's Water. He was bald — as he told the court — and he'd changed in himself too. He'd got asthma and that's what worries me now about his lung.' She said gently. 'You think he's tough, but it's his conquest of himself that makes him so…'

'All this doesn't make Caldwell my father.'

She said softly, 'You remember the cairn on the Oyster Line, John. The little boy? It was probably a gang of the Hottentot refugees and riff-raff which used to terrorize those parts in the early days who took him. Dad didn't know your story until I told him on the way to Walvis bay. Dates, times, age — everything tallies. Tregard the missionary was your foster-father, you know that, but what about where you really came from. You were the little boy. Your mother was murdered.' She made a curious, heart-warming gesture towards the other bunk. 'He's suffered greatly, John. He discovered the Oyster Line and he came back to… well, to that cairn of stones. The diamond fountainhead is his — it's his dream, his life, — and then the bitterness of finding it hopelessly inaccessible, beyond his power to break open. He has sat his life away on Mercury, watching, waiting, hoping…' There was a long silence. The only sound was the creak of the cutter's anchor cables. 'When he heard about you, he turned the Gquma round then and there. You were in grave danger, he said, something big was about to happen. He risked his life to fetch you.'

He must have known that the gas barrier was due to burst.

'Why didn't you ask him…?' I began.

The voice from the bunk, though weak, was resonant. 'Why don't you ask him yourself?'

Mary went over and took his arm from under the blanket. She crooked it in hers and at the same time drew me over, linking her free arm in mine. Caldwell tried to smile, but it turned into a grimace of pain and a fit of coughing. Mary wiped away the pinky foam.

I said awkwardly, 'We could have saved all this… The Mazy Zed offer…'

He replied, with a flash of his old self, 'You've got to get out of this bay quick, boy.'

'You'll be fine, once we get a doctor to you…'

He shook his head. 'It wasn't that I was thinking of… maybe I will, or maybe not. But there's a barrier of methane gas…'

'It's going to burst.'

'Yes,' he answered. 'I thought you must have worked it out, the way you set off inland. Yes, John, it's going to burst. I've waited a lifetime for it to happen. Once or twice it was pretty close, but it didn't come off, and the long wait began all over again. It's not a thing a man can do anything about. The old underground river floods when the rains are heavy on the mountains behind the desert. For it to be as it is now there must have been once-in-a-lifetime floods. When it breaks, it will sweep the diamonds out to sea — Oranjemund won't be in it…'

The Bells reverberated against the Gquma's hull.

'The whole bay is shaking like hell,' I said. 'Mercury is the centre…?'

'Yes,' he replied weakly. 'Mercury is the fountainhead of the Sperrgebiet.'

I couldn't forget the dead men. 'You tried to scare off the Mazy Zed rather than share it.'

Mary darted an angry glance at me, but Shelborne said, 'No, John, it wasn't that way. Strangely enough, I wanted to save lives. Yours, Rhennin's, those on the Mazy Zed. When the barrier goes, it will take everything with it — maybe Mercury too. Hundreds of thousands of tons of gravel and millions of gallons of water will be unleashed. In prehistoric times before the continent lifted, the flushing process was easy because the floods had freeway to the sea. If the Mazy Zed had been operating,' she would have been swept away like a twig in a maelstrom. So I used scare tactics, but they got out of hand — the Bells, the gas, the rest of it. Somehow in my life every good motive of mine has boomeranged and turned out wrong.' He smiled, but it was edged with bitterness. 'Caldwell's luck, you know. Mary has told you, of course?'

'Yes. What about the Praying Mantis?'.'

'I intended to wreck her and to rescue you all with the flatboom. I didn't bargain for a storm like that. I reckoned that once the survey vessel was out of the way, you'd stick to other places and not come back. I wasn't to know you were on to the fountainhead idea.'

'And the attack at Angras Juntas?'

He tried to shrug and his face went white with pain. Mary intervened, but he waved her aside. 'It wasn't the People's Second Atlantic Group, or whatever they call themselves, but a more private enterprise — a Polish fishing outfit based on Conakry, near Freetown. They run the occasional parcel of stones into West Africa for me, for a consideration, to keep my prospecting efforts going. They were only too pleased to have a crack at the opposition, but there again things misfired. They promised me they would do no more than inflict superficial damage and create enough rumpus to keep you away from Mercury. By the time you were able — or wanted — to get here I hoped the barrier would have exploded and the thing would have solved itself. But they took it as an opportunity to try to sink the Mazy Zed…'

'And Sookin Sin?' He hadn't heard about it. It was, we agreed, a clumsy attempt to try and shift the blame on to the Russian trawler fleets of the coast.

He was very weak, but I had to find out why he had helio-ed along the river march and where his water had come from.

'It wasn't a helio, John, but my water-maker. I learned it in the Takla Makan; it's a wooden-frame, covered with glass, with little gutters on the inside. You saw its reflection. In clean-blown sand like the Namib it is simple to find water, if you know how. Water will sink only a certain distance in dry sand. I've known places in the desert where some scanty rain has lain as a moist layer for years a couple of feet below the surface. Here on the coast with our heavy fog-dew the water lies close to the ground-level, but if you dug, all you'd get would be slight dampness. My sunbox draws it up, it condenses on the glass, and I tap off pure water via the little gutters. It gives, about a brandy bottle full a day — I lived like that for a year in completely waterless areas.'

He coughed and closed his eyes. Caldwell the legend had beaten the desert at its own game!

I didn't like the sound of his coughing. 'I'll get the sails on her,' I said.

'I'll help,' said Mary. There's not much I can do here.'

Shelborne had not exaggerated the handling qualities of the Gquma. The sun was low and the wind fresh from the south-west. We set all plain sail and she snored out of the bay with the starboard rail awash. At this rate, we'd make Walvis Bay in two days. Mary sat by me at the long-handled tiller for an hour or more until Mercury was out of sight behind the northern arm of the bay.

I turned to look at the wake to estimate our speed.

'Dear God!' exclaimed Mary.

The double doors of the coach-house in front of us flew open. Shelborne stood, a great crimson blotch across the white bandages.

His voice was strong, excited. 'John! Mary! Did you hear it!'

We exchanged glances. There had been no sound but the wind; we had left he Bells behind after clearing the bay.

He steadied himself on one of the bad-weather grab-handles, gazing hard out astern — towards Mercury. He cocked his head. 'It's come, John! It's come, Mary! Look! What a sight! The whole shoreline is being swept out to sea! There's never been a flood like it!' He lifted his hand and Mary stopped on her way to him. 'Listen! Hear that! — Mercury gone! Poor Mercury! — it was home to me for so long…' There was no sound except the creak of the boat and the thin whine of the wind in the rigging; the shore was invisible. 'The Mazy Zed will take diamonds for twenty miles out now, John! No need to worry about the methane problem any more.' He turned towards the tiller, but he didn't see me: his eyes were blind with agony. 'My special suit of sails — this is the occasion I made them for. Bring her round so that the wind is more aft, John… we'll get them up…'

His grip relaxed and he fell dead in the bottom of the boat.

It was five minutes before I could bring the Gquma to a halt. She lay pitching in the long swell. Mary knelt by him.

Then we heard it for the first time — the long shattering thunder of the break-through. Caldwell had waited a lifetime, but he lay lifeless before the sound could have reached us.

We stared at one another.

Mary said, 'He was given to hear it — before.'

We broke out the new suit of sails.