‘Go for it.’
Jack finned forward over the lava, watching the streaks of red in the cooling lobes and nodules directly below him. At about the halfway point he was suddenly surrounded by a miasma of bubbles escaping from the lava below, a silvery mass that seemed to waft around him, bathing him in refracted light. He lost all points of reference, and seemed to be falling precipitately, a feeling that made him want to let go of the line and spread-eagle himself like a skydiver. His hand jerked on the line and he twisted sideways. It was no illusion; he really had been falling. He began pulling himself along, his buoyancy computer continuously adjusting to compensate for the effect of being dragged down in the vacuum created by the bubbles. He reached the grapple, checked that it was locked securely into a crack and then turned to look for Costas, who had crouched down on the edge of the tunnel opening, holding the line. Jack held on to the rock face with one hand and put his other out in the diver’s okay signal, his forefinger and thumb joined in a circle, and then transferred both hands to the line. He heard Costas’ voice crackling on the intercom through some kind of interference, the broken sounds briefly becoming distinct. ‘You ready?’
Jack wedged his body as much as he could into the rock. ‘Roger that.’
Costas launched himself forward in a slow-motion dive, his bulky suit making him look like an astronaut. As the line went slack, Jack hauled on it, looping it quickly around a rock protrusion behind him. It suddenly went taut as Costas was sucked down by a gas plume and disappeared out of sight. The line went slack again, and for a horrible few seconds as he frantically pulled on it Jack thought that Costas might have impacted with the lava. Then the crackling came on the intercom again, and Costas appeared out of the plume and ascended a few metres below him. He reached the ledge beside Jack, then wedged in an elbow and took the grapple gun out again from his pocket, unhooking the line from the carabiner on his chest and feeding it back into the tube. He glanced at Jack through his visor. ‘That was close.’
‘Your boiler suit looks like glue.’
Costas grunted, reached into the crevice to disengage the line from the grapple, then pressed a control on the tube to re-spool the line and hook it back into the second grapple, ready for firing. He wrapped his hand round the grip again and peered at their objective, the rock-cut platform in front of the ancient entranceway some fifteen metres away. ‘Twice lucky?’
‘Go for it.’
There was a jolt as he fired the device again, and Jack watched the grapple arc over and disappear into a fold in the rock about a metre below the ledge. Costas pulled hard, and the line went rigid. He leaned back and Jack swam over him, taking the line in one hand and kicking out above it. This time he quickly made it to the opposite side and Costas followed, swimming forward while Jack hauled, not bothering to loop the line but letting it drop down below. Costas reached the rock beside him and hung on, breathing heavily on his regulator, then he grasped the line near the grapple and let go of the rock to release the carabiner. As he did so, Jack saw a white expanse of gas billow up below them, and at the same moment the rock holding the grapple broke free under the tension and tumbled off the face, dropping down below Costas into the fomenting mass of bubbles now rising up around them. Jack wedged one hand into the rock and reached down with his other to grab Costas under one arm, holding tight as the plume rose through them. For a split second it seemed as if they were dangling in air, and Jack was holding Costas’ entire weight. Then the plume dispersed above them and Costas hit the manual on his buoyancy control. Jack twisted round and looked up, seeing the carved lintel shape above the doorway, straining to look for the ancient symbols he desperately wanted to see.
Just as he relaxed his hold, there was a jerk and Costas’ arm slipped away. Jack twisted back and saw a horrifying sight. Costas was at least five metres below him, his arms flailing, descending fast. Jack slammed his buoyancy control to dump the air inside his compensator and swam downwards. The chunk of rock with the grapple still inside had pulled Costas down like an anchor, and was now embedded in the lava near the edge of the chamber, sinking in and pulling Costas with it. Jack reached him with only a few metres to spare, pulling his chest strap with one hand and releasing the carabiner with the other, then injecting air into both of their buoyancy compensators. He watched the line snake away and disappear into the molten mass below them, and turned Costas round to face him. ‘You okay?’
Costas was wide-eyed, his visor fogged up around the edges from his exhalation. Jack had a sudden sickening feeling. They had just lost their one lifeline, and they had expended more air than they had bargained for. Costas returned his stare. ‘I think that’s twice very lucky,’ he said hoarsely. ‘Let’s get up there, do what we have to do and get the hell out of here.’
As they swam upwards, Jack turned to look out over the lava lake. A surge was rising in the middle, then moving along as if something were swimming just beneath the surface like some ancient spirit monster. Suddenly the mass rose in a giant bulbous dome and split open, disgorging a huge bubble of gas into the water. A second later there was a blinding flash and Jack could see the pressure waves in the water surging towards them. Costas clung to him, pressing his visor against his. ‘Brace yourself!’ The shock wave pushed them violently towards the rock face, and then they were pulled back again over the lava lake by the implosion. Jack held on to Costas with one hand and finned with all his strength back towards the rock-cut door. He seemed to be getting nowhere, as if this were a bad dream, the door impossibly beyond his reach. Then the sucking force of the implosion miraculously relented, and they came to the ledge below the door.
‘What the hell was that?’ Jack said, panting.
‘Phreatic explosion.’ Costas’ visor fogged up as he struggled to regain breath. ‘It happens on land when lava flows over pockets of water, superheating it. Somehow that big bubble of gas under the surface of the lava must have had the same effect, sucking in water, encasing it and boiling it up.’
Jack stared up at the carved lintel above the doorway in front of them. Costas followed his gaze, panting, then he saw what Jack had seen. ‘Symbols. Ancient writing. Is this what you saw before?’
‘It’s fantastic.’ Above the doorway was the rectilinear Atlantis symbol, with other symbols on either side, familiar from the syllabry they had discovered five years before but not yet translated. They looked freshly carved, as if done just before the flood, and several looked only partly completed. Beneath them Jack could make out other symbols, very eroded and clearly much older, some of them looking as if they had been partly chiselled away. He activated his camera. There was no time for detailed recording now. He was jittery with adrenalin, and checked his computer readout. Fifteen minutes of breathing gas left at this depth. He was conscious that the danger had made the reflective part of his mind shut off in the focus on survival, on dealing with each new threat as they encountered it, and that he needed to maintain an awareness of the bigger picture, of just how close they had come to never leaving this cavern alive. He stared at the entrance. He would need five minutes, just to look. With the lava rising inexorably, it was the last chance before whatever lay inside there was lost forever.
‘Jack, you’ve got a problem.’
‘What is it?’
‘Check your internal temperature readout.’
Jack looked sideways inside his helmet, scanning the digital readout. ‘Twenty-six degrees Celsius. I thought it was getting a little warm. I’ll adjust the thermostat.’
‘Don’t do that yet. Wait till you really need it. You’ll blow the system.’
‘What do you mean?’
‘It must have been the heat when we were close to the lava. You’ve got a leak from your coolant reservoir, Jack. You can’t afford to be that close to extreme heat any more, as you’ll soon have no way of cooling down.’