with only a metre or so of clearance below the collapsed rock. He followed Costas, inching along. He heard the three Russians close behind, scraping and clanging their tanks as they hauled themselves along the passage, the exhaust from their breathing cascading along the cracks and fissures above Jack. He swore under his breath. If they caused another rock fall, nobody would be coming out of here alive. He concentrated on looking ahead, and saw that Costas had reached the end of the sump and had knelt up out of the water. Jack came alongside, and broke surface. They had come nearly to the end of the rockfall, and could see the end of the tunnel about ten metres ahead, half submerged.
‘This must be where the vertical shaft begins,’ Costas said. ‘I’m looking at my atmospheric sensor. There’s still oxygen here, but methane as well in pockets against the ceiling. Probably breathable, just.’
‘Won’t be like that below,’ Jack said. ‘From what Wlady said, we’ll have to assume any gas pockets are methane.’
They crawled and waded forward, past a ledge that had once been some kind of loading platform. A massive rusted pulley mechanism hung down from the ceiling where the track ended. It was a winch for a lift, but the metal cable was missing, evidently cut off or rusted away and dropped down the shaft with the lift platform. He looked back and saw the first of the Russians haul himself out of the water, spit out his mouthpiece and wheeze heavily, his hands on his knees. Jack turned back, and saw Costas’ fins sticking up. He pulled himself along, below the winch. The view over the edge was astonishing. Costas was hanging upside down, his headlamps aimed down a vertical shaft lined with timbers. The coppery green had gone, and the water was extraordinarily clear. Jack could see down a phenomenal depth, but still not make out the bottom. It was an awesome sight, spine-tingling, as if he were looking down a shaft into the centre of the earth. Costas craned his head up, looked at him. ‘You good with this?’
‘Good to go.’ They had been in a mineshaft before, just like this, when Jack had run out of air and nearly died. But now was not the time for flashbacks. Survival instinct overrode that. He remembered Rebecca, why they were here, and steeled himself. He watched Costas drop head first down the shaft, and then followed him. The water was so clear that it was as if he were jumping into air, and he instinctively put out his hands and feet to catch himself on the wooden beams, to stop himself from falling headlong. He made himself straighten his legs and hold his hands ahead like an arrow, spiralling down behind Costas. They dropped quickly, twenty metres, thirty, forty. He was grateful for the automated buoyancy control, the computer that sensed their speed of descent and kept it in check. He tilted his head so that he could see directly ahead. Far below them, thirty or forty metres perhaps, he could now see the glimmerings of the base of the shaft, a mass of collapsed metal machinery lit up by their headlamp beams. Two minutes later they were nearly there. ‘Let’s go neutral,’ Costas said. Jack pressed the manual buoyancy override and injected air into his suit, then tucked into a ball and rolled upright so that he came down feet first like a parachutist. He injected more air to stop just short of the coiled pulley cable and iron platform, coming to a halt alongside Costas. They both looked up. A confused mass of bubbles and light beams moving to and fro was visible far above, where the Russians were coming down.
Jack looked at his depth gauge. Ninety-five metres. He turned and aimed his beam horizontally into the passageway they were about to enter, the level that would drop at a thirty-degree slope towards their target area about a hundred metres ahead. Costas came alongside and did the same. An extraordinary vista opened up before them. It was clear that they were following a natural fissure in the rock, just as Wladislaw had predicted, with outcrops of halite crystals visible. The crystals shimmered and sparkled as they panned their headlights over them. The fissure had once formed a series of interconnected caverns, but the narrower spaces between the caverns had been hacked away to create a continuous tunnel wide enough for a narrow-gauge track to be laid, identical to the one they had followed at the higher level. Jack could see the track continuing for about thirty metres and then ending at a point where the rock had been left untouched, a much narrower gap. They swam slowly forward. On either side the indentations formed deep chambers, some crudely hacked into a rectilinear shape, one of them with a half-built wooden door and wall enclosing it. Tools lay strewn around, whitened by salt precipitate growing over them. At the end of the track they saw the railway car, a standard narrow-gauge hopper small enough to be pushed by miners, containing a wooden cradle as if some substantial piece of equipment had been carried in it to this point.
‘This tunnel doesn’t look like salt mining,’ Costas said. ‘It looks like someone was building a storage facility.’
‘And then abandoned it halfway,’ Jack replied. ‘None of the side chambers are finished.’
‘The Nazis?’
‘It’s difficult to see why miners might have come down here. This deep, it may often have been flooded, by changes in the water table like the one that causes the water to be so deep now. The odd thing is, it might make sense for Neolithic miners to have got this far underground when it was dry, making their way down the natural fissure where that shaft is. We know that Stone Age painters could get a long way into cave systems. And they may have been looking for especially prized halite crystals only found this deep. But for later miners with metal tools, there was a lot of salt still to be dug out much closer to the surface.’
They reached the end of the metal tracks. Jack rolled over and looked up, seeing the shimmering surfaces of pools where methane gas had accumulated. He looked back to the end of the shaft, where the first of the Russians had appeared. ‘Christ. They’ve come all the way down. At least fifteen metres beyond the safe depth with trimix. About where nitrogen narcosis will really kick in too.’
‘Drunk, narked and on a one-way ticket to hell,’ Costas said.
‘But dangerous. Did you see their knives?’
‘Roger that. Let’s get this done.’
They swam forward beyond the end of the track, through the crack in the rock. Ahead of them the fissure carried on as far as they could see, with a crudely cut pathway along the floor. On either side were shimmering crystal caverns, some with halite crystals five or six centimetres across. Costas was ahead, and after only a few metres he stopped and sank down to about a metre above the floor, over an area where the crystals seemed to be remarkably uniform in size, as if they had all grown from the same genesis. ‘You remember Wladislaw and his dating of the salt growth to the Neolithic? Take a look at this.’
Jack peered down. Beneath the crystals was a shape, staring up at him. He had seen this before where calcium carbonate, precipitated minerals, formed stalagmites over bones, but never with salt. It was a human skull. He saw a ribcage, leg bones, arms laid over the chest. He could just make out chipped and polished stone tools laid alongside, hand axes and adzes, several still attached to wooden hafts. ‘It’s a burial,’ he murmured. ‘Maybe that’s what these people were doing down here as well, using it as a burial chamber.’ He stared again at the skull. The jaw had dropped, as if it were leering. He remembered the grim sculptures they had seen in the passageway with Wladislaw, the one that had reminded him of Munch’s The Scream. Perhaps this was what those medieval miners had seen. Perhaps it was not their own mortality they feared, but some terrible demon of the depths they had encountered down here – in a place that perhaps was never broached again by the miners, and was only reopened when the Nazis decided to create a top-secret storage facility in these depths.
‘My sensor registers almost zero oxygen in the water,’ Costas said. ‘That’s why it’s so clear. No life here at all.’
‘Ten metres to go, according to my map,’ Jack said, peering into the tunnel. ‘I think I can see something at about that distance, ahead and to the right. A small cavern entrance, maybe. Something blocking it.’
‘Jack, there’s something strange about the floor ahead of us. Odd shapes.’
Jack dumped air from his suit and sank down, staring ahead. Too late he realized that he was going to hit the bottom, and he silently cursed. He prided himself on his buoyancy control. And in caves, silt could be stirred up with barely a touch and completely obscure visibility. He injected a burst of air into his suit and just avoided impact, but watched a pressure wave from his body ripple through the silt ahead. In a fleeting second he realized what Costas had seen. Bodies. Human bodies. Lying on either side of the path. But not solid bodies. As the ripple passed through them they disintegrated and exploded upwards into the water, a great cloud of white particles and flakes that engulfed Costas and wafted towards Jack.
‘Thanks, Jack. A swim through disintegrated human flesh. That rounds off this little excursion nicely.’
Jack swam forward, dropping down into the haze. He saw skeletons, two, three along one side, picks and crowbars strewn haphazardly around, the bones wearing the remains of clothing. ‘This looks a little more recent than our Neolithic friend,’ he murmured. ‘The shoes look pretty modern.’
‘Are you thinking what I’m thinking?’
