Neptune's Brood

by Charles Stross

  There were no more worm-mats, after that first near-disastrous encounter. Twice I came close enough to see ghostly pisciform hunters, feral mechanocyte colonies that had accreted around a dream of fishy form. Eyeless, they had circular, tentacle-rimmed maws, the tentacles branching into a fuzz of—well, I was at pains not to get close enough to examine them in any detail. My guide capsules could emit a searing flash of light, and a shrieking band-saw rasp of noise that drove them off if they tried to approach me. And I am not inclined to go looking for trouble.

  After the third platform, I saw no more living things. The water was acrid and unpleasant, and I felt that I ought to be choking in it. I was swimming through the anoxic depths, far below the level at which photosynthetic organisms could oxygenate the waters: What life existed here was forced to subsist on the anaerobic decomposition of the steady thin rain of disrupted cellular debris that fell from the world-roof high above. Not much of anything that was big enough to see with the naked eye survived down here.

  But once, in the distance, my eyes registered a faint blue glow, pulsating. I thought I was hallucinating at first, before my guide capsule chirped up: “Attention, Krina! Danger! Radiation hazard below!”

  “Wait, what?”

  “Danger! Avoid radiation hazard below!”

  “What is it?” I turned, triangulated. Heard hissing, sizzling—felt the first distant touch of heat against my skin. The blue glow was becoming more intense.

  “Danger! Avoid rad—” The guide capsule’s warning tempo became urgent, and suddenly I realized what I was seeing. Half-panicking, I turned and shoved myself away from it as fast as I could, until the glow faded from sight.

  “Am I clear yet?” I demanded, my motor groups painfully aflame with excessive exertion.

  “Stand by. Clear. Krina, wait here for half an hour. Avoid radiation hazard.”

  “Was that a blue smoker?”

  “Krina: Blue smokers are radiation hazards.”

  So yes, it was a blue smoker. I shuddered, half-disbelieving. I’d been lucky enough to see one of the wonders of the known universe with my own eyes—and I’d survived.

  Shin-Tethys is a young planet, and this is reflected in its isotope balance. Among other corollaries of this is the fact that much of the uranium 235 that was present when it formed has not had time to decay; uranium found locally is around 1 percent U-235. When volcanoes erupt on the surface of the mantle, down in the mixed rock-and-ice-VII crust below the bottom of the sea, the magma they eject is rich in uranium. And when the magma bubbles up through the rock and the ice and encounters seawater, well . . .

  On Old Earth, the Fragiles’ birth world, the floor of the oceanic abyssal plains were punctuated by black smokers—volcanic vents from which issued streams of superheated, mineral-rich water, under too much pressure to boil but hot enough to melt lead. The black smokers in turn supported complex ecosystems, as rich minerals precipitated out of the hot solution rising from their chimneys and provided warmth and nutrients in the chilly depths.

  Blue smokers are not so friendly to life.

  Rising magma meets rock and dissolves it, then boils up into a layer of heavy water ice. This is not ice as we know it, under Fragile-friendly temperature and pressure conditions. Ice under such immense pressure transitions to a different, denser crystalline structure: one that is denser than water, so that it sinks to the bottom of the sea. When magma meets heavy ice, the ice melts, forming a mineral-rich liquor at very high temperature. The bolus of molten minerals rises, melting its way through the ice progressively, until it reaches open water, still hundreds of kilometers below the surface.

  As to why it remains liquid . . .

  Neutrons from naturally fissioning U-235 meet the hydrogen nuclei in the ice and water. Hydrogen is a moderator, slowing fast neutrons, making them easier for heavy nuclei to capture. The rate of fission shoots up, achieving criticality. The bolus of molten minerals gets hotter, roiling and glowing blue with Cerenkov radiation—photons emitted by particles traveling faster than the speed of light in water. If it gets too hot, the water molecules break apart into gaseous hydrogen and oxygen, and the nuclear chain reaction slows—but then the water molecules re-form under immense pressure, and things pick up again. The only constant is the radiation. And the bubble of dissolved uranium salts, of course, fissioning merrily away like a deadly kettle.

  Blue smokers—feral uncontained fission reactors—periodically wander up from the depths. It can take weeks or months for them to reach the surface thermocline, driven by the pressure gradient: Finally they pop, exploding in a gout of viciously radioactive steam while still below the surface of the sea, sending a dome of whitewater and finally a mushroom cloud boiling up from below. Along the way, as they rise, they wreak havoc. A blue smoker will kill anything and anyone too slow and stupid to get out of the way—it will kill them just as dead as any other uncontained nuclear reaction, cooking them thermally, then with slow neutrons and gamma radiation. If you want to dispose of a corpse, a blue smoker is the ultimate in waste-disposal tools.

  They have other uses.

  If you can break a blue smoking bolus of fissile uranium-laden water apart with water jets, you can cool it down. And then you’re left with a mineral strike of incredible value: thousands of tons of saturated uranium solution, rich in U-235 and plutonium isotopes. Blue smokers tend to repeat in the same crustal area, time and again, bursting out like geysers. Frequently they erupt on a schedule regular enough to set a clock from. The farther down you capture your radioactive nightmare, the less of its fissile material will have decayed. And so the maniacs who mine the blue smokers of Shin-Tethys do so as deep in the abyssal depths as they can venture.

  I watched, from a borderline-safe distance, as the faint blue glow of a lethal treasure strike wobbled and shimmered up from beneath the path I had been following. Finally, my guide capsule chirped up: “Krina, resume descent. Calculating detour.”

  “Okay, I’m moving.” The guide beam snapped on again, pointing prudently away from the smoker, and I stroked into motion again, following it into the gelid darkness.

  * * *

  More than forty kilometers above me, a confrontation was in progress that, had I known of it, I would have been agog to witness.

  Picture first the sequence of events that unfolded aboard the Chapel of Our Lady of the Holy Restriction Endonuclease, from the hijacking a year ago to the moment of arrival in orbit around Shin-Tethys. The designated leader of the mission, Lady Cybelle, is once again incarnate—and asking awkward questions of Deacon Dennett, who, in her absence, has been behaving most erratically. (His harebrained scheme to reboot her in a weakened, easily manipulable mind-set while making use of the chapel’s tankage for smuggling appears to have failed, thanks to the untimely intervention of a piratically inclined insurance agency.)

  She is not enchanted to discover that two-thirds of her original crew have died or deserted. Neither is she charmed by her new and dubious minions, Cook and my stalkerish doppelgänger. And she is positively devastated by the discovery that her precious freight of Fragiles are all dead, killed in the same accident that cost her a body. That the Gravid Mother thinks she can gestate a fresh brood of neonates with which to continue the holy mission is scant consolation, for they will be immature on arrival and require years of additional curation and conditioning before the holy ritual of Planetary Colonization can be attempted (even if it terminates, as is usually the case, with the immediate demise of the Fragiles upon their exposure to the alien biosphere).

  If it was necessary to select a single word to describe the atmosphere aboard the chapel after my departure, that word would be “poisonous.” And this condition prevails even before we consider that Lady Cybelle is now aware of the precious treasure beyond all comprehension that slipped through her fingers before she was sufficiently compos mentis to recognize me from her mission briefing.

 
(That’s got to hurt.)

  Picture now the arrivals and immigration processing hall adjacent to the capsule dock through which Rudi and his minions—and I—entered Nova Ploetsk. A fast ballistic descent capsule chartered even before the chapel entered co-orbit with Highport sits, steaming gently, on the decking of one of the subsurface hangars in the reception suite. A motley crew of sacerdotal pilgrims are forming up beneath the critical gaze of their leader; all wear the ritual space suits of their order, joints subtly reinforced and motorized to provide support in the unfamiliar gravity well. Behind them, an automated loader is extracting body-sized capsules from the lander: the first strange fruiting of the chapel’s well-stocked ossuaries.

  “Father Gould, if you would be so good as to wait here, with the relics”—Cybelle does not wait for him to acknowledge her instructions, but turns to Dennett—“you will accompany me. And you.” She makes eye contact with a figure that bears a disturbing resemblance to one Krina Alizond-114. “Stay with me. Do not speak unless spoken to. Remember who you are.” Or, more accurately, remember your role. “Now, attend.”

  The priestess turns and, surplice flapping around the boots of her space suit, marches toward the immigration gateway with the curiously stiff-legged stride of one who is not entirely in control of her own endoskeleton.

  The reception awaiting an ordained priestess, heading a formal mission from the Mother Church, is very different from that which is given to a suspiciously underdocumented accountant in the employ of a firm of insurance underwriters turned space pirates. Rather than a cramped capsule ride to an office staffed by a bored and paranoid instance of the Queen, there is a sweeping row of shallow steps descending into the hip-deep warmth of a receiving pool, where a mermaid stiffly awaits her arrival, an expression of hauteur on her face, and a retinue of secretaries and assistants and constables to pay court to her.

  Cybelle advances on the queen-instance without hesitation. “All honor to Your Majesty! I am Cybelle, Priestess-exultant of the Chapel of Our Lady of the Holy Restriction Endonuclease, here by decree of our Mother Church to discharge our Holy Mission of Colonization in respect of Dojima System.” Something that might be mistaken for a smile twitches her cheeks. “May the peace of the Mother Church and the blessing of the Fragile be upon Her Majesty, Medea of Argos, Queen-creator regnant of this laminar kingdom of Argos, and all her subjects.”

  She makes the ritual sign of the double helix; the mermaid ducks her head briefly, while behind her, the audience watches with appropriate respect.

  “We are indeed Her Majesty, Medea of Argos, acting here in our capacity as immigration comptroller general of my own domain.” The mermaid fixes Cybelle with a direct, inquisitive stare. “Welcome to Argos.” There are no overt entry formalities here, although the chapel’s flight clearance and passenger manifest has been registered with Argos’s immigration database for over a year now. “May we inquire as to your intentions here?” Argos is not a huge nation, and to be singled out for the attention of the Church’s mission to the entire star system is cause for pride if not anxiety.

  “Certainly.” Cybelle inclines her head. “We have brought our holy relics to meet their final resting place, to claim this planet in the name of Humanity Fragile But Triumphant. It is our intention to remain in orbit until we can conduct the Holy Colonization itself—alas, our actual incarnate passengers are not yet of an age to participate—while in the meantime tending to the pastoral needs of the people of this world. If Your Majesty approves of our proposal, we should like to base our primary mission to Shin-Tethys in your lovely and hospitable nation.”

  Medea’s expression stiffens very slightly. “In principle, we believe your desire can be accommodated,” she replies. “However.” Her gaze tracks past Cybelle, taking in the members of the missionary delegation. “We have some questions that require answers.” Her gaze stops, locking onto one particular gowned and space-suited figure, sans helmet. “We see some faces that were not listed in your manifest. And one in particular that is disturbingly familiar.” She pauses for a couple of seconds. “Krina Alizond-114 disappeared under suspicious circumstances while helping the police with their inquiries, and who now appears to have returned. Constable!” A uniformed officer steps forward. “That person. Her presence is anomalous, and she is, in any event, assisting your department with its inquiries while awaiting possible indictment for immigration offenses. Arrest her at once, on my cognizance.”

  Heads turn, surprised and disconcerted, as the constable salutes his ruler, then turns and strides through the water. It supercavitates on contact with his legs, churning up in a foam of bubbles that does not noticeably impede him: He might as well be walking across dry ground.

  The doppelgänger, immersed up to her waist in the pool, doesn’t hesitate. Her suit seals burst open, and she erupts vertically from her garment’s embrace, her agility absurd, implausible; she leaps across the pool, using the backs and shoulders of the members of Cybelle’s mission as stepping-stones, punching any who try to catch her.

  The cop spins round and charges after her, shoving apart the bunched clergy and the gaggle of courtiers who attend the Queen: More constables burst into sudden motion around the room. Two of them move to block the overwater exit, at the far end of the pool. Another moves to guard the entrance, while more move to encircle the impostor. The doppelgänger responds by changing direction, charging toward the Queen. Her feet splay out, toes webbed and impossibly long and wide as she races across the surface of the water, kicking up a wake. Medea slumps backward, sliding rapidly beneath the surface and reaching up to grab at the impostor from beneath.

  “Stop her—” the Serjeant of Police roars from behind, wrong-footed by her initial feint and still trying to catch up. “Don’t let her get—” The mermaid Queen dives, arms grabbing at the impostor’s feet. Beneath her, a barely darker circle of blue outlines a concealed underwater exit from the pool, debouching into a flooded tunnel: But the doppelgänger shakes herself clear of Medea’s grasp. She drops a fist-sized object as she races toward the overwater exit at the far end of the room.

  There is a concussive blast from behind her, and a tower of water splashes against the ceiling, drenching everyone still standing. Then, as she reaches the exit, a crackling series of shaped-charge explosions crosshatch it with blinding flares of light.

  Silence briefly falls above the bloody water, which is streaked with emerald green circulatory fluid. Courtiers are panicking and Cybelle’s delegation cower as the room fills with constables, the air above them a-bristle with quadrotor knives and combat hornets. A new door opens high in one wall, and a water slide extrudes above the pool. The seal shapes of hunter-killers slide down it, take up positions in the water to either side: Then another mermaid enters the pool, this time quite clearly in a towering rage.

  “Bring us my sister’s soul chips!” she commands her minions, gesturing at the mortal wreckage of her sib. “Then retrieve the regicide.” Her glare takes in the visitors. “We will hold court with you later.”

  “But the assassin’s dead”—the constable, still shocky, gestures at the smoking wreckage of the exit—“probably too chewed up to be any use.”

  The newly arrived instance of Queen Medea bares her teeth. “This game has gone on for too long and is no longer a pleasant distraction. We have questions that urgently demand answers. And being dead won’t save Ms. Alizond—or whoever she is—from delivering them.”

  * * *

  Iswam for what felt like years, although in all likelihood it must only have been a handful of days—in decimal, at that. At regular intervals, I found more buoys, with platforms suspended from them, laid out with guide capsules and comestibles to keep me fed during the trek. I do not know for a certainty, but I believe that at no point did I actually ascend from one buoy to the next: They were all positioned at ever-greater depths, so that by the time I reached the final platform I must have been at least forty and p
erhaps fifty kilometers below the surface.

  There were no more mats of predatory worms, or blue smokers. As I dropped farther into the abyss, the clicking and chittering and wailing noises faded toward a barely audible background, almost entirely above me. While I knew that there was almost 150 kilometers of open water beneath me, what I fell through was almost empty: anoxic, gelid, mostly clear of turbidity in my guidance beam (which was increasingly difficult to follow due to the lack of scattering).

  I became deathly afraid of losing my direction, of falling, or of swimming headlong into the depths. I knew that I was as close to crush-proof as it is possible to engineer a body to be: But when water itself comes under such pressure that strange, anomalous phases of ice that are denser than liquid are stable, who knows? I maintained the routine of pausing on each platform, waiting for equilibrium, waiting for the self-destruct warning that presaged each oasis’s collapse and slow descent toward the unseen graveyard floor of the world.

  I had, as should be obvious, a very long time to think about recent events. My thoughts were not, for the most part, happy ones. When I commenced my study pilgrimage, I had expected to face years of privation and frequent loneliness punctuated by intense and rewarding study with my peers. I’d anticipated an interesting session with Ana, trying to trace the provenance of the furtively purloined slow money certificate that Andrea and our accomplices had abstracted from the dusty vaults of the bank: I had expected to return home in due course, still bearing the certificate from Atlantis, which could be returned to its resting place with no one the wiser.

  I had not anticipated that word of its existence would leak; that an assassin wearing my face would chase me to an unexpected watery destination, that everybody would be unpleasantly interested in my activities, that word would come of Sondra herself turning her vigilant and vengeful gaze toward me.