"There's something else," I said.

"What's that, son?" Ortega asked.

" 'Save our ship,' " I said. "And when we got blasted by that static a while ago, Gina heard the words 'help us.' "

"Are you sure of what you heard, Lloyd?" Hancock asked her.

"As sure as I can be, Gunny. It was faint . . . real faint, almost not there at all."

"I'd say that this code we're hearing validates what she thinks she heard," Montgomery pointed out. "You know what that means, don't you?"

"What?" Hancock asked her.

"That white sphere out there is what's left of Murdock Base . . . and there are still survivors on board."

"My God!" Hancock said.

"She's right," I said. "It makes sense. The wreckage of the base would sink to the point where it was the same specific gravity as the water around it. Or maybe it sank until it's floating on that gelatinous liquid ice."

"But the base wasn't a sphere!" Ortega said.

"No . . . but they would have had an external nanomatrix, same as we do," I said. "Suppose they programmed their external nano to grab water molecules and reassemble them into hexagonal crystals."

"Freeze them, you mean," Hancock said.

"Freeze enough of them to make a giant ice ball," I said, nodding. "To withstand the increasing pressure as it sank."

"That's . . . crazy . . ." Hancock said.

"I don't know how else they would have survived the pressure this deep," I said. "If they were sinking slowly enough, they might have been able to keep adding on more and more ice, and letting the ice get squeezed until it was essentially incompressible. If their original dome was CM, it might work."

" 'Save us,' " Montgomery said. "A call for help. . . ."

Save us . . .

At dead-slow speed, we continued our approach to Sierra Five.

Chapter Twenty.

"There's something else," Montgomery said as we approached the huge dull-white sphere adrift in the eerie light. "The cuttlewhales . . . they deliberately brought us down here. They want to help!"

"Looks that way," Ortega replied. "Still, we're best off if we don't jump to wild conclusions."

"What else are we supposed to think?" I said. "It would have taken us over a day to get down here at a steady descent rate of ten meters per second. That cuttlewhale swallowed us, brought us here, and let us go, bang on target."

"Where is that cuttlewhale, anyway?" Hancock asked.

"Astern," Lloyd said. "And drawing off. I'm picking up a lot of them in the area . . . over two hundred. They seem to be keeping their distance."

"They dropped us off, then withdrew to a discreet distance," Montgomery said. "To observe? To appear non-threatening?"

"Maybe just to watch what we do," Hancock said. "And speaking of which . . . what can we do? If Dr. Montgomery is right and that's our base . . . we're going to have a hard time just getting in there. And the Walsh is way too small to take more than a handful of survivors to the surface at a time."

"How many people were stationed at the base?" Lloyd wanted to know.

"Eighty-five humans," Hancock told her. He glanced over his shoulder at D'deen, still unconscious in his bowl, before adding, "And twelve Brocs."

"Ninety-seven," I said, "would make things a bit crowded in here."

"How thick is that ice?" Ortega asked.

"The original central dome of the station was about thirty meters across," Hancock said. "That sphere is . . . what? A hundred meters wide?"

"Almost that," Lloyd confirmed. "Sonar readings give a diameter ninety-eight point one meters."

"Close enough. So assuming the base itself is at the exact center of all that, it's underneath a minimum of thirty-five meters of super-compressed ice."

"It might not be that bad," Lloyd said. "We have a see-through."

One of the bulkhead viewalls brought up a translucent image of the sphere. "Sound waves travel through solid structure," Lloyd told us, "and their backscatter can give us an idea of what's inside."

"Sonograms," Montgomery said. "So where's the baby?"

"We can see a kind of hollow area inside," Lloyd said. On the image, the dome inside the ice, given a yellow color by the computer, had a broken, crumpled look, but a deep purple blob at the center suggested an internal void. A slender purple shaft ran from the interior space to within a few meters of the outside surface.

"What's that?" I asked. "An access shaft?"

"I think so," Hancock said, studying the image closely. "I'm not sure how it's holding up under the pressure, though."

"The borders of that shaft are CM," Lloyd said. "I think they must have built it by cannibalizing other parts of the dome itself with construction nano."

"It certainly looks like the way in," Hancock said. "Let's get in close."

The Walsh slowly moved to within twenty meters of the sphere and carefully circled it, probing with her sonar. Lloyd was using a lower-frequency pinging now, the better to penetrate ice and CM metal, but there seemed to be no response from the distant, watching cuttlewhales. Perhaps they'd thought of the earlier, extremely loud sonar pulses as a hostile act, but now knew that we were using them to feel our way through the depths.

At close range, we were able to get a bit more detail on the sunken base's interior, but not much. Sound imaging is wretchedly imprecise for fine detail, compared to electromagnetic radiation. We couldn't tell if there were people moving around inside or not. It was all blobs and fuzziness inside.

"The survivors have stopped banging," Hancock observed.

"They probably heard our sonar," Lloyd told him. "They stopped to listen."

"Give them one ping . . . then two more."

A moment later, an answer came back. Clank . . . clank . . . clank.

"I'd say we've established communications," Montgomery said.

"Great," Ortega said. "So what do we do about it?"

"We see about getting inside," Hancock replied. "Lloyd? Take us in close. Put us up next to where that long passageway is."

"Aye, aye, sir."

The Walsh was completely coated by a thin layer of nanobots-the source of our external light and our vid imaging from the outside. In addition, large portions of the hull were titanoplas nanomatrix, meaning the individual particles of matter could rearrange themselves in order to, for instance, change the submarine's shape to give more or less lift as she flew through the water. It was the matter of a few moments to program most of the external 'bots, directing them to migrate to the port side and begin building a docking collar. Doing this cost us most of our external vid. We kept a few nanobots in place as image receivers and transmitters, as well as some light along our port side. To starboard, above, and below, the ocean deeps returned to a primordial blackness punctuated, surprisingly, by flashes and ripples of pastel-colored light in the distance. Evidently, life within this ocean world, as on Earth and as within Europa, had learned the trick of generating organic phosphorescence.

Slowly, a squat cylinder began to grow out from the Walsh's port side, burrowing into the wall of ice alongside.

The toughest part of the process was working against that incredible pressure outside. One advantage of working at nano scales, however, is the obvious one that a nanobot has much less surface area against which the weight of the water can press. One square micron is one ten-thousandth of a square centimeter; each individual 'bot was experiencing something like ten kilos of pressure, a hell of a lot on a device a fifth the size of a human red blood cell, but not impossible. Each individual device, working with molecular motors and minute electrical and magnetic fields, was incredibly strong. The speed of each device was considerably reduced; under these pressures it would have taken days, perhaps weeks to erect the dome instead of a couple of hours. A docking collar was a lot simpler than a habitation dome; our AI predicted that the construction time would be about eight hours.

We had Walsh's small on-board nanufactory put together dinner for us. Then we slept in our seats, with Hancock, Lloyd, and myself sharing the watch, staying awake to make sure everything continued to proceed as planned.

Eventually, the docking collar was complete, creating a solid connection between the newly grown airlock in Walsh's port side and the end of the purple void buried about ten meters back within the ice. Much more difficult than growing the thing, though, was depressurizing the collar once it had been extended out from our hull nanomatrix. Our fleet of microscopic construction engines had burrowed away into the ice, hollowing out the space inside the collar by decoupling the oxygen and hydrogen from each other, breaking water ice into gasses that promptly vanished into solution. Once the ice was gone, however, it had been replaced by liquid water.

Fortunately, that water was not at the outside ambient pressure. Water is not compressible . . . meaning that if the docking collar carried the weight of the water outside, the water inside remained at a more sane pressure. So long as there was no break in the seals or any opening to the outside, the interior of the collar was as safe as an Earthside swimming pool.

We still faced a problem in getting the water out of the collar. The traditional means-using air pressure to force the water out-wouldn't work here, not unless we had a pump that could deliver more than one hundred tons per square centimeter.

The answer was to grow a reservoir alongside the collar and pump the excess water into that. Eventually-another couple of meals-the water was gone from the collar, replaced now with air from Walsh's reserves at standard temperature and pressure.

Meanwhile, we had other external 'bots working outside the sub and the docking collar, creating layer upon layer of compressed ice to build up a strong pressure shell. Walsh, by this time, was firmly bonded to the ice sphere enclosing the base, nearly lost within the much larger mass of ice.

Oddly, though, we'd stopped hearing any of the banging communications from inside. We tried both radio and sound, but there was no reply, an ominous silence that had Hancock worried.

"I don't like it," he said, staring at the inner hatch of Walsh's new airlock. "What happened to them?"

"Maybe their arms got tired," I suggested.

"Very funny."

"Look, are we sure that collar is going to hold the pressure?" Ortega asked. "If that collapses after we open our hatch . . ."

"It's as solid as we can make it, Dr. Ortega," Lloyd told him. "The collar is holding the pressure now just fine. That won't change when we crack the hatch."

"Then let's get on over there," Hancock said. He looked at Gina, then at me. "Doc? You with me?"

"Let me get my M-7, Gunny."

We'd discussed procedure exhaustively during the past day, going over the situation and searching for anything we might have missed. Hancock would go first . . . just in case, because he was our only Marine. I would go with him because I was the Doc, and there might be-probably were-people in there who needed medical attention. We'd considered donning our Marine armor, but eventually decided against it. The long, narrow passageway into the interior of the ice-shrouded base was only a meter and a half high and wide. Mk. 10 suits were just too cumbersome and bulky to allow for easy maneuvering in such a cramped space.

The only reason to wear armor would be if the air in the long access tunnel wasn't good, but nanoprobes had already reported that the atmosphere beyond the docking collar was breathable, a standard oxygen-nitrogen mix, at one standard atmosphere. It would be a bit chilly over there, and the humidity was near 100 percent . . . but we wouldn't need to carry our own air.

Gunny Hancock produced a weapon-a holstered 12 mm Republic service pistol-which he holstered on his hip. I'd not even known he'd brought one along . . . but then, the idea of a Marine going anywhere without at least a sidearm when the tactical situation was unknown was . . . unthinkable.

Besides, the survivors in the sunken base had been here for weeks now, presumably. We might need at least the threat of firepower to maintain control.

I hoped that would not be the case.

I stood with Gunny as he opened the Walsh's inner lock.

"Doc?" Gina said. "You be careful over there, okay? Make sure you come back."

"Always," I told her, grinning. "Careful is what I do best."

At first I was touched that she seemed concerned for my safety. Then I realized that a likely reason for that concern was the fact that if anything happened to us, it would happen to the people left on board Walsh as well. It was easy to forget just how unforgivingly deadly this environment truly was. And the wrecked dome inside its ice ball would be dangerous, if the shell was already partially collapsed.

We moved through Walsh's airlock, and opened the hatch between the collar and the airlock. The air inside was thick with moisture, steamy hot, and with water dripping down the bulkheads and collecting on the deck. Both ice and CM are excellent insulators, and the interior was still hot after driving off most of the water.

Good.

Hancock opened the collar's outer hatch, revealing yet another doorway beyond. This one looked . . . strange, not like a typical base airlock access at all. It was solid dark-gray metal, with no obvious way of opening it.

It gave us both pause. "What the fuck?" Hancock said, looking the barrier up and down. "You know, Doc, I think-"

The barrier opened of its own accord, the metal puckering at the middle and then rippling open in all directions, creating a circular opening, a doorway leading into near total darkness. And beyond, within that darkness just a couple of meters away, loomed a shadowy, monstrous figure . . . an armored Gykr.

"Get down, Doc!" Hancock screamed, drawing his weapon. The Gykr already had a weapon in one of its forward appendages, a complicated-looking tube with a massive grip designed for its manipulatory claspers.

It fired, and I heard a sharp crack and smelled the tinny stink of ozone as a bolt of energy snapped above our heads and slammed into the docking collar's outer hatch behind us. Hancock brought his pistol up and got off two shots. The Republic 12mm was an old-style slug-thrower, but had the considerable advantage of not requiring a heavy battery or other power supply. Both rounds, however, appeared to shatter against the Gucker's carapace without effect. Hancock must have loaded the seven-round magazine with frangibles . . . a good idea if you were planning for a firefight within an enclosed environment where putting a round through a bulkhead was not recommended, but useless when it came to penetrating armor.

Hancock cursed, came up off his hands and knees, and collided with the Gykr soldier. The only light was coming from a few nanolights in a circle around the outside of the docking collar behind us; inside the long access tunnel beyond, it was completely dark, so much so that I couldn't see if there were more Gykrs waiting for us farther along.

For a moment, Hancock and the Gykr struggled, and all I could see was a confusion of spidery limbs around the black, central mass of the alien; then the Gykr fired its weapon again . . . and again . . . sending one bolt into the overhead. The second burned through Gunny Hancock's left arm.

He screamed and sagged to one side. I'd been looking for an opening, but the passageway was too narrow for the two of us to engage the Gucker at once. Now I was able to crowd past Hancock and grapple with the Gykr hand-to-hand . . . or maybe, in this case, it was more hand-to-hand-to-hand-to-hand. The Gykr had several limbs that could serve as legs or arms, and several small arms that were useless for heavy lifting, but which could grasp and claw at me.

"Get him up!" Hancock screamed at my side. "Get him up!"

I saw what he wanted. Normally, Gykrs went about like giant insects, heads low to the ground, their rounded backs well protected by bands of artificial armor grafted on over bands of natural calcareous armor or chitin. Their undersides were less well protected, especially around the face and mouth parts.

Grappling with two of the Gykr's longer arms, including the one wielding the alien weapon, I dug in and pushed, hard, lifting the creature up and back. I was aided by the gravity, 9 percent less than Earth's, and doubt that I could have lifted it in a full G or without a personal exoskeleton suit.

I managed to push it up and back, however, its legs flailing as it tried to get a grip on my body. Hancock's pistol went off right beside my ear, a painful, thundering crack-crack-crack that left my ears ringing, but the rounds slammed into the thinner armor covering the Gykr's face, ripping open its suit above its breathing flaps.

From the autopsy Chief Garner and I had performed, I knew that there were six breathing slits along its head, three to either side of the being's face behind and below the bulge of its compound eyes. Gykrs breathed oxygen, though they needed a lower partial pressure than did we-about 10 percent.

But they also appeared to need a higher level of carbon dioxide-over 33 percent-a level that would have been fatal to humans without breathing gear, and they required an ambient atmospheric pressure a third lower than ours.

As I wrestled there in the dark with that armored horror, I could hear a hissing, rasping gurgle as it struggled with the tunnel's gas mix forcing its way into its suit. I freed one hand, stuck two fingers into a gaping hole opened by one of Hancock's bullets, and yanked as hard as I could, peeling open a layer of artificial outer armor as thin as paper.

The Gucker broke free from me, staggering backward, its arms flailing wildly, its weapon landing with a splash in a shallow pool of water a meter in front of me. Ducking down, I scooped up the weapon, wondering how to fire it . . . and then finding the trigger recessed into the grip. The bolt slammed into the Gykr's chest, burning open a ragged crater the size of my head and dropping the struggling creature onto its back.