The splash was followed by another, and another, marching closer and closer to the catwalk. She could see something in the filthy water, something mottled gray and big. Quite big. Suddenly it shot forward in the water, headed straight for the walkway-

And Nikha narrowly stepped aside as it heaved part of its stinking bulk up onto the brick, leaping so hard it smacked its front into the wall. She fired at it, but the angle was bad and she could barely keep her feet after dodging. The bullet just winged it, releasing a spray of dull blue blood before impacting in a puff of dust. Her hearing went muffled and gunsmoke stung her eyes She only caught the barest impressions of it before it slid back into the water: gray topped with white, fat, amorphous, a fin running along its flank like fringe.

In the water it splashed a few more times, then circled round and came in for another charge. She was ready for it this time, waiting for it to choose a line then leaping back as it hove up on to the walk. It shoved up onto the brick with a sound like a dog on a hardwood floor. She aimed and yanked the trigger, only to find it dead. She hadn’t reloaded! “Oh, you fool!” she hissed as she fumbled a new round into the breech. As she raised the lever and pulled back the hammer, she looked up and finally saw her foe clearly.

The…thing, for lack of a better word, was the size of a pony and shaped like a short, fat slug. A continuous fin circled its gravid body, segmented by clawed spines. Its skin pulsated in sick shades of gray, and on its back was a smear of shingled, keratinous growths that curled and split like untrimmed fingernails. She saw no eyes, but as it heaved itself closer it reared up, revealing a slitlike mouth fringed with feathery tentacles. Revolted, Nikha put a shot right between its lips. The bullet punched right through it, releasing another gout of blue fluid.

The creature made a high-pitched gargle and leaned back even farther, piling up on itself like a sack of lard. Nikha cranked the spent round out with a jolly clang! and quickly shoved in another. Risking a glance backward, she saw uncomfortably little room left before it would have her backed up against the far gate. Returning her eyes forward, she nearly gagged at what she saw. The slug everted a rugose, purple-gray sac from its mouth, floppy and pebbled with tiny spine-like teeth. The smell was indescribable. It made a choking sound, wobbling back and forth in its precarious position. Nikha realized what was happening just before it did.

She stutter-stepped backwards until she hit the wall as the slug toppled down at her, its sac-tongue slapping down onto the bricks- and onto the toes of her boots, wet and heavy and hotly alive. Nikha let out a shriek of outraged revulsion and sent a half-inch bullet down the whole length of its body, muzzle blast crisping its skin. Blood and unidentifiable organs blew out of the massive exit wound, and while the thing jiggled and fluted in distress it kept shoving at her, fin-spines scrabbling for purchase. She slashed at it with her bayonet, swinging had enough to slice its tongue to ribbons even at this awkward angle. That finally got its attention, and with a spasmodic wriggle it flopped awkwardly back into the water. Nikha reloaded fast as she could, sent a bullet into the spot it had sunk, and reloaded again. She nearly kept shooting, but some heretofore-undiscovered reservoir of calm made her forbear the waste of ammo.

She was breathing hard and fast, heart pounding, her skin clammy with cold sweat. For a few seconds she squeezed the stock of her gun so hard the wood creaked, and she nearly began to cry. No, said that calm part of her. I can’t break now. I’m not done yet. She hitched in a deep breath, held it, and relaxed, unclenching her fingers. A few more of those and her heart rate slowed. A few more than that and she almost felt normal.

The pumps were still running, giving Nikha a moment to think. She kept one eye on the water, but the level was far too low now for the slug to leap back up- and that was if it hadn’t bled out. She’d made a mistake back there, and then almost lost control. Neither were something she could allow herself. When I’ve found Papa and things are back to normal, I can curl up into a ball and cry all night. Until then, though… Until then, she had to be hard, as strong and hard and disciplined and vicious a soldier as she could be.

She used the last few minutes of pumping time to take stock. Her gun’s action was getting sticky, a sure sign it needed cleaning. Both of her knives were dulled and would take a good bit of sharpening. She’d bled through the bandages on her hand, and they needed changed. And most unpleasantly, her boots and the hem of her dress were covered in inky blue blood which she had nothing to wipe off with. All in all, she needed a place to stop, a real, safe one like Papa’s study.

When the growth-clumped bottom of the depth gauge finally emerged from the water, Nikha grumbled “Finally,” and went to throw the lever. But then an idea struck her and she let the pumps run a while longer. The water level had already gone down about twelve feet, and went down several more before she saw the lumpen back of the slug emerge from the water. It was wiggling fitfully on the canal bottom with no way of getting to her. A cruel and eager grin pulled across her face.

She took her time drawing a bead on it, enjoying the chance to shoot something outside of bayonet range, and squeezed the trigger. A thump to her shoulder, a teeth-rattling boom, another spray of blue blood. The beast hooted like a blown jug and thrashed harder. Brass jangled on the brick as she reloaded. The next shot burst something inside it, splattering oily, pus-yellow ooze onto the water’s surface. The slug gurgled, its movements slowing. “One more,” Nikha murmured, still smiling. She put a final bullet through what she thought was its front. It stopped moving instantly, going limp. Good.

The slug was probably just a dumb animal, and Nikha wasn’t the sort of person to do things like burning ants with a magnifying glass. This was different, though. The thing had tried to kill her, and wherever it was from it certainly didn’t belong here. She wasn’t above being happy it wouldn’t bother her again.

A hard shove of the lever got the pumps running again, covering the slug’s corpse. She filled the chamber back up to the low mark on the depth scale. Then she shut them off, let boiler pressure build, and finally threw the lever for the lower gate. There was a great bang that shook the whole tunnel, a tortured howl of metal, and for a moment she thought the works had jammed and she’d be stuck in this tiny room forever. Then the doors split with a crack! and began to open, scabs of rust the size of dinner plates falling away into the water. The engine chuffed and thudded and hidden gears squealed and clanked, starved for lubrication. The noise of it all was nigh-on intolerable.

After nearly a minute of mechanical cacophony the gate opened enough to clear the walkway. Nikha set all the levers back into neutral, shut off the phlogiston, and opened the dump valves. No sense in letting a boiler explode under her house- if she was still under it at all.

A flight of stairs took her down to the lower section of the canal, their treads scooped out and made treacherous by dripping water. This part of the tunnel was in poorer condition. The walkway was heaved and off-camber as if subsiding into the canal. The ceiling fairly drizzled, fallen bricks littering her path. It didn’t take long for her to become cold and soaked, her hair hanging in lank strands down her back. She almost stopped to get out her coat, but decided she’d rather just push through. It was then that she came upon another side door.

Nikha stopped and stared at it, shivering a little. Maybe there’s a nice warm den in there. Or a sunny balcony. If the house sent her all these bad places, it would have to send her somewhere good eventually, right? Even the room full of fire might be nice right now. She had to at least try. She set a clammy hand on the latch and pulled the door open.

For a brief moment Nikha was filled with elation. There was indeed a sitting room in there, dim but for a fire crackling merrily in a hearth across from the door. That feeling immediately turned to trepidation when she saw the room was occupied. A small dog was curled up on the rug, facing the fireplace. A man was seated in a chair beside it, the flames silhouetting him in profile. As the door creaked open, he stood and moved into the light.

He was tall, his walk jerky, and his face doughy and strangely proportioned: the nose crooked, the eyes too small behind his glasses. Something about him set her immediately and severely on edge, like a cat with its hackles raised. Nikha set her face and reached for her gun.

“Hello,” said the man in a high, quavering monotone. “I am a human person.” He waved at her with both hands. It took her a moment to realize what was wrong with them: they were identical. Two lefts. “Would you like to have a conversation together?” One of his eyes began sliding down his cheek, still fixed on her. Behind him, his dog stood and turned around. Its tail wagged but it had no head, just a blunt, furry pseudopod. Nikha made a small squeaky noise and slammed the door hard. No more side doors, she decided.

She stomped ever on, leaping gaps in the causeway, occasionally tripping over solid holes, and staying as dry as she could- which wasn’t very. Finally the canal ended, or at least her path did. Before her was a cave-in, a massive pile of mud, scattered brick, and twisted metal bars. She could hear water sluicing through but there was no way she herself was getting past. Luckily there was another path. Below a sputtering arc-sconce on the wall was a gate more rust than iron. It hung ajar and Nikha went through, glad to leave the dank tunnel behind.

The brick ended at a stout slate threshold, giving way to natural rock. There were no lights, so Nikha got out her lantern. The walls were milky-pale flowstone, organically smooth and slick. Water trickled down them-or up them- and pooled in low spots on the wavy floor. Nikha had to tread very carefully, her movements tense in the poor light. The flowstone was shiny, even translucent; it reflected the light strangely, bouncing glare into her eyes and making it hard to know where to put her feet. Once her foot slipped out from under her on a hidden slope and she barely caught herself, barking her knee painfully on the tunnel floor. She braced a hand on the wall as she stood, but jerked it away when something twitched beneath it.

Nothing was there, even when she held the lantern right up to the spot. Nikha squinted at it with worried dissatisfaction. She couldn't’ afford to be surprised. She moved the lantern to a different angle, casting shadows obliquely across the stone, and finally saw it. There wasn’t anything but stone there, but the stone itself was moving. It pulsed with a slow, regular beat, like a blood vessel or a breathing animal. Like something alive.

Nikha stared at it a few seconds, squeezing the lantern’s handle, then let out a shaky sigh. Nothing she could do about it but take it in stride and watch to see if it got worse.

It did. More and more parts of the tunnel throbbed like veins, expanded like lungs. Sometimes the tunnel grew narrow and they moved against her, strong as the rock they were made of. The lantern either dazzled her or cast stark shadow, concealing more than it illuminated. The strange, melty-curved shape of the tunnel made her splashing footsteps reverberate back and forth until she couldn’t tell the real ones from the echoes. It was like traversing a bad dream.

She could have been in there five minutes or five hours, and already she was missing the canal. The cave’s course heaved and twisted. Sometimes she had to scrabble up near-vertical slopes on her hands and knees, bracing as peristaltic shudders of the rock tried to throw her down. Other times she navigated pinched corners that felt like they might trap her, or shoved her pack ahead of her before crawling through a low-ceilinged pinch point. The overall direction was still downhill. She wondered if she’d passed into the Earth Gullet like Ytakhos from the Originatia, if like that accursed king she would walk forever beneath the earth, moving ever deeper. Momentary reflections from down the tunnel made her jump and freeze, waiting with held breath. The darkness beyond her lantern was absolute. She felt a mad desire akin to that felt by someone atop a steep cliff, a temptation to turn off her lantern and stand still, to let silence fill her ears and feel the black emptiness smother her, crush her like a physical thing-but the thought was far more terrifying than it was seductive. She pressed forward, face in a taut grimace, squinting past her lantern’s glow.

There was a timeless interval where she almost felt separated from her body, when she was unsure whose legs were stumbling over the twitching floor, whose fingers were cramped around the lantern’s grip. Then Nikha noticed a light ahead, steadier than any reflection. For a moment she thought she’d gone mad. Then she shook her head, coming back to herself. With sickly horror, she realized she’d nearly just…gone away, there. Given up and consigned herself to the darkness. Papa was depending on her. She had to stay focused.

The light ahead was a rich azure, far bluer than the phlogiston arc of her lantern. Unsure of its origin, she awkwardly shuffled the rifle into her hands, holding the lantern clasped to its forend. She needn’t have worried. The light came from a strange, glass-and-iron lamp hanging from an iron hook above an archway. It was the first thing of human construction Nikha had seen since leaving the canal. Keeping her gun up, Nikha passed into the room beyond.

The space was vaguely circular, with a high ceiling. A few more of the blue lights shone on the perimeter, dim but steady. Closing in on one, she saw it was actually inside the wall, covered with translucent flowstone. It must have been here a while. Other things were in the rock as well, trapped like insects in amber. Squinting, she thought she made out a table covered with small metal tools, each with its own halo of rust. Farther off there was a dark rectangle that might have been a wall tapestry. Even the floor showed strange carvings trapped beneath inches of accretion, their shapes flanged and unfamiliar.

Nikha made her way across the cave, arms out for balance on the slippery floor. Oddly enough, none of the stone in here seemed to move. Wait, why is it odd when it doesn’t move? She shook her head. Across from the door was a pair of the blue lights mounted on tall iron stands. Between them was a huge, waist-high block of old bronze, green-black with age. It stood mostly proud of the wall, but a tide of flowstone had covered it like candle wax. Nikha crouched and held her lantern up to it, trying to make out what was carved into its side. There was a mandala-shape like those she’d seen elsewhere, surrounded by runes in a language she didn’t recognize. With its shape and flat top, it looked like an altar. Several feet deep in the flowstone behind it was another shape. The stone was less clear here, and Nikha couldn’t really tell what it was. A statue, maybe? Something about it reminded her of the thing in the gallery- No, don’t you dare- so she tore her eyes away.

Nikha carefully followed the wall, looking for an exit. She saw more metal tools inside the wall, their shapes blurred by rust. Relief carvings too, depicting strange, almost abstract narratives. People kneeling before huge geometric shapes. A moon folding open and surrounding a sun. A man staring into the sky, and the sky staring back with an eye broad as heaven. There was even something in there she thought might be a corpse, though it was too far away to tell.

Finally, she found an exit, a cage-like door made of old wood. The whole thing was covered in flowstone clear and shiny as ice. She chipped it away from the latch with the pommel of her knife, then had to spend another few minutes chopping the bars free of the floor and ceiling. Finally she was able to shove the door open enough to squeeze by.

Past it was a blue-litten cave passage, though this one had been artificially widened. Nikha could see the chisel marks beneath their coat of glassy stone. She wondered briefly if the moving rock felt pain when it was chipped away. Going was still slow, but faster than in the first passage thanks to more room and more light. And even better, this tunnel sloped upward! It wasn’t as wet here, and her exertions began to dry her clothes. There were even guide chains bolted to the walls, though they were uselessly sealed behind an inch or more of accretion. The path took her up a long flight of stairs that was now more like a ramp, up a ladder whose slippery iron rungs nearly sent her plummeting on a ten-foot fall. At its top was a wooden trapdoor whose coat of flowstone cracked away after a few awkward whacks of Nikha’s hand.

Pushing through, she climbed up into a stone corridor-manmade, not a cave. Gas lamps burned low on the walls, their light shockingly warm after so long staring into the blue of her lantern. She closed the trap behind her and looked around. She’d emerged at one end of the hall, its floor and walls were of rough blocks of pale stone. They were bare and windowless. Like a dungeon, she thought. Supporting this was a series of barred doors along both walls, identical and evenly spaced. No way was she messing around with those. She stood up and walked smartly down the hall, luxuriating in the light-

“Is someone there? Hello?”