"Should we try it?" asked Barendts, gesturing to the laser rifle still held in the sub's metal arms.
Rue pictured them bickering while their only chance drifted away behind them. "Let's do it."
Barendts sat down in the copilot's chair, rubbing his hands. "Action at last," he muttered, setting his hands on the controls for the manipulator arms. He had been practicing over the past days, learning how the limbs amplified his own movements. Once he'd gained confidence, he and Herat had gingerly transferred the laser rifle from the large arm it was hanging off to a small set more suited to fine work. Then they'd fired a test shot with the laser, just to make sure it would work.
Herat's plan was brutally simple. The front part of the sub was an egg made of transparent diamond-matrix. Behind that was more ordinary machinery, made of metallic hydrogen impervious to almost any pressure. The lasers of Barendts's former friends had wreaked havoc amid this machinery. It was dead weight now: ballast. Herat proposed to cut it away.
Rue kept watching the gantries slide by while they maneuvered the arms around to aim the rifle at the back of the sub. Suddenly she saw a glimmer of bright light ahead and above— a line on the ice ceiling that rapidly grew into an oval of glowing green. "Look!"
It might have been a natural formation— a weaker and softer core of ice that had melted upward, forming a natural dome in the ceiling kilometers across. One or two nukes could have carved it out in seconds. As the highest point for many kilometers around, such a dome would naturally pool any gases that bubbled up from the ocean depths. Humans could as easily have pumped nitrogen and oxygen into it, until now there was a round cathedral of ice, hundreds of meters of airspace above the ocean, lit with floodlamps and with many buildings bolted to the ice around its periphery. Rue stared, fascinated, at spindle-shapes bobbing in the water that must be the hulls of boats or subs like the one they were in now.
The whole cavern was only a few kilometers across. "Hurry, or we'll miss it!" Rue said. Barendts was frowning, obviously trying to decide what structural members of the sub to cut first.
"Fuck it," he said. A line of bright blue light suddenly joined the laser to the back of the sub. Bubbles shot up in a row from a centimeter or so above this line and bright flares of light splashed out from the back. Barendts waggled his hands and the bright line zipped back and forth, impossibly fast.
The sub lurched. Rue watched a large piece of machinery plummet into darkness. "Good," she said. "I think we're rising."
"Just to be sure," said Barendts and waved the beam again. Bright sparks flew and abruptly the cabin lights went out and the noise of fans that had been omnipresent for days, ceased.
"Oops," said the marine. "I guess we're committed now." Rue could barely see his shrug in the blue glow from the approaching cavern.
They were rising, but not fast enough. Rue watched in frustration as bright water began to scroll past overhead. She saw catwalks, boats tied up just meters above them.
"Maybe we should swim for it," she suggested hesitatingly. Herat shook his head.
"We'd freeze to death or drown— or both," he pointed out. "Listen, Barendts, does that laser have a flashlight setting? Maybe we can get someone's attention."
"Good thought." The marine pointed the laser upward and fired it. The bright blue light jutted up, throwing wild shadows across the wavering image of the cavern's ceiling.
"No flashlight setting, by the way," said Barendts, just before a huge chunk of ice slammed into the water meters away. "But that ought to get their attention."
They were barely a meter below the surface now, but the current had taken them almost all the way across the cavern. She saw the ice ceiling coming up again ahead of them.
Suddenly light flooded the cabin. Underwater spotlights had come on around the periphery of the cavern. Now the sleek shapes of divers appeared in the water, wrapped in bubbles like spiraling wings. Six or seven of them swam after the sub.
"Here we go," said Barendts. The lines of blue light shot out from the vicinity of the divers and sparks flew right below where Rue was standing. She jumped in surprise.
The sub's manipulator arms, including the laser rifle, sank quickly out of sight. One of the divers approached them, his own rifle held out prominently.
Barendts grinned. "This is the part where we put our hands up," he said, demonstrating.
Three of the other divers were towing lines. They attached these to the sub and soon they were on the surface, being towed toward a set of docks where a number of other subs lay at berth.
"Let's get out of here," said Rue. She headed for the hatch. Herat laughed and shook his head.
"We never equalized pressure, at least not as far as I can tell from our busted instruments," he said. "The air out there will crush you like a grape if you open that hatch."
"Oh." She pointed at the divers now squatting atop their hull. "Do they know that?"
"Let's hope so." The divers hopped off, into the water, and their sub was hoisted out of the water. As it slowly turned, water rolling down the sides, Rue got a good look at the cavern they had come to.
Halfway up the blue wall of the cavern, a huge opening gave onto an even larger space, this one well above the waterline. The cavern they were in was just a lower dock area for what looked like an entire city carved out of the ice.
"What are those?" Tall shapes like smooth stalagmites stood in bright glimmering ranks under the lights of that other cavern. Rue pressed her nose against the diamond hull and peered at them. As the water stopped running past her eyes, she got a good look, but still couldn't figure out what she was seeing.
"They look big, but what are they?"
"Autotroph technology?" asked Mike. Barendts shook his head, pointing down at the docks below. Men in uniform were running about there; none were the conspicuous green of the fanatical humans who had seemed to worship the autotrophs.
"Hey, what are they doing?" protested Rue. The sub was being lowered into what looked like a giant trash compactor. It was a heavy cube with airlock hatches on the sides and top. It was attached to a larger, windowless cube. Their view of the cavern beyond was cut off as the cube's walls rose around them; then they were grounded with a thud. Fit-looking young men with buzzcut hair hopped into the cube and proceeded to roll the sub on its side. Stuff fell about the cabin and Rue found herself skidding over to sit on the wall.
Now their airlock was right next to a door that led into the larger cube. The fit young men clambered out of the cube and its walls started closing in, accompanied by a deep throbbing of motors somewhere. This is it, thought Rue incredulously, they're going to squash us.
The sides of the door to the large cube flattened and deformed around the sub's hatch, as though it were made of rubber. The sub settled a bit, creaked and then someone was undogging their hatch from the other side.
A little puff of air came in. A man-sized robot stood there, little laser lenses aiming at them from its hips. It stepped back with a clank and gestured in a very manlike way. "Come in," it said.
Rue and the others climbed out of the sub, finding themselves in a large cube-shaped room with bunks along the walls and a small partition behind which there was a toilet. There were no windows.
"Pressure equalization will commence now," said the robot. It slammed the inside door of the cube and stood in front of it, arms crossed.
Herat went over to it. "Please don't equalize the pressure," he said. "We need to get back to the surface as soon as possible!"