The hammer crashed into the railing of the bridge on Zone Three. Ghulzar struck again, and again, with the strength of mad rage, announcing his presence like a warrior at war drums. It wasn’t a metalsmith’s tool, but a weapon after all. Between the crashes, splashes echoed; then the patter of wet hands over the pipes. Did it even matter if the dwarf told Plamen what was happening? Who could even guess how many were swimming up right now through that channel?

The first appeared on the north wall, to my left, lizard-like. Glistening-wet, it gibbered into the light of the lanterns the other smiths had left. A second crawled in from the right, grappling among the thinner feeder pipes, and stopping. Freezing in the gloom. Ghulzar saw them, both of them, and held position. I held my breath and took the slowest backstep I’d ever taken. Stilled my body. Membranous lids flashed over the shiny-black stones of their eyes in those pale heads. Knotted tails of hair dangled, dripping. Their mouths were small ‒ I didn’t think their jaws could open very wide ‒ but they were snarling, baring needles in muddy gums, trailing thick spit. Just run, I tried to will myself. By the time any soldiers got to us, it wouldn’t be about holding the fortress anymore. Today Antissa could fall and there he stood, one crazy metalsmith—its sole defender. Why shouldn’t I just run? This wasn’t home! I was the borderland boy, just a Naemian refugee.

And—it hit me—more Antissan than I’d ever been Naemian. Or ever would be.

The one on the right sprang to Arte-III, from there to Ghulzar’s bridge and I nearly did run. But it wasn’t even that simple: I knew how fast they could move, how far they could leap, and if I ran, I’d only get one chance. Low on its haunches, the Rath wheeled a half-spear.

Before it launched, Ghulzar charged it. He undercut its jaw with a rising sweep of his hammer, which flung its body to the railing.

The other leapt out from the wall. For a sickening second, I lost all sight of it in the shadows, then saw the scuttling of long limbs on a higher feeder. From there it dropped, dodging the hammer, just as a third pair of hands grabbed the Zone Three bridge from below. More black eyes followed.

Spinning from his miss, Ghulzar brought the iron down again and smashed those fingers. A screech tore free and echoed out across the breadth of the zone as that one dropped, hitting another lower pipe and disappearing. Two more replaced it: I saw them clinging, spider-like, to the bridge’s under-frame.

The rising numbers made a chorus of fast-pattering hands, and my stomach plunged when I saw the wall of movement seething through the gloom. I had to go now. Had to run.

The narrow, sinewy jaws snapped at Ghulzar’s fists as he now grappled for his own hammer. He thrust the weapon’s handle into the nose of the creature he faced, making it stagger; that gave him time to change his grip and crush its skull, while the new arrival on the sub-frame hissed and launched back through the open. There it latched its legs around another feeder and watched from just outside the light. Triglycerate flickered on its eyes.

‘Pelkh-spat demons, I’ll take you!’ roared Ghulzar.

He’d die trying. I knew he would, unless help came. And though it hadn’t been my choice, this was home now. Another home about to crumble.

My mind raced, scanning the arterial towers. The Sight had done something, I realised now; heightened the way I looked at them—my awareness of the water, as if my seeing its true paths had left an imprint in my head! Locking my eyes onto a sub-gauge of Arte-III, suddenly I knew I could do something. Buy Ghulzar time. But only if I moved right now. This second. The boy of the borderlands could run. Just not the Chief's boy.

I was running already, before fear stopped me again, but wasn’t going for the tunnel. My running jump cleared the railing of the second zone bridge, blackness below, before the sweep of rope-nets caught my fall. I glanced back as the net rocked and creaked under my landing—no followers!—then scrambled up towards the sub-gauge. I’d sealed it once; now with my hands on both its levers, I pulled them hard towards me.

Now down! Don’t look, just climb.

But the snarls and croaks wafted up and I couldn’t help but watch the fight on Three. Ghulzar held his bridge, cursing the creatures as they came. White spear-wielding spiders, they fanned around him. He raised his iron, made another charge and swept two right off their feet with the hammer’s handle, then crushed their heads. Another reached him in two leaps, but he was quick; he ducked away from the lunging spear, swung low and broke both of its knees. Disarmed, another dodged a blow to its chest before it followed the others back out into the dark.

Shaking, I scaled my way to the next girder. I dismounted from the net, moved around the column of Arte-III, stepped into gills and started down.

Clawed hands now swiped for Ghulzar’s face. The hammer swung again to strike the pipe beside him like a gong, and bodies dropped. From the north, four or five more groped from darkness. The Rath in front of Ghulzar fell, its head shattered and flapping on its shoulders, but now those five at the end of his bridge had turned to eight. Not counting the half-lit limbs that scuttled on the sub-frame.

He gave the bridge up.

Rath on his heels, I watched him sprint to where the cantilever abutted the side of Arte-III, reach for its gills and start climbing towards me. ‘Other way!’ he bellowed up.

‘I have to open the sub-valve on third zone!’ I yelled back, shaking my head. ‘Could force them—’

‘You got some kinda death wish? There’s no time!’

Below the man, the numbers thickened, then I screamed as two sets of arms and legs wrapped around him, claws closing fast around an ankle. He booted one in the teeth and broke its grip, let the hammer fly across his wake in an arc that struck the face of the creature behind it and plucked it from the pipe. From the cantilever sub-frame, more Rath sprang onto the surface of the bridge. Five—seven—nine—too many! And no longer any way of reaching the gauge on that zone. He was right, there wasn’t time, so I turned and climbed back up the way I’d come down. Ghulzar behind, Rath in pursuit.

But I couldn’t stop looking down. ‘Your back!’ I cried. The hammer swept to fling the closest chaser like a toad. Two more leapt in to replace it, but the hammer, rebounding, took them both. The weapon was a pendulum, sacred as every muscle and tendon of the arm that made it swing. As soon as it stopped swinging, I would die.

At least a dozen climbed the arterial and more than twenty were on that bridge.

Then two soared off their haunches, spinning spears in mid-air. They latched onto Ghulzar and, with force, wrapped him in a tangle that pulled him clear of the gills and down, ploughing a path through the upward-crawling mass and sending several Rath skating off the sides. It was over.

But by some miracle, he was still there when I dared to look back down again; swinging from the bridge where his sudden halt had jerked the Rath to his legs. Now they dangled from him, gnashing.

The sacred hammer was gone.

‘Get out! Out! Out!’ he roared at me, grip straining, and I knew there was nothing I could do.

Behind, below, the numbers swarmed.

Then—snapsnapsnap!—bolts flew and peppered chalky flesh. Screaming, the danglers let go of Ghulzar, fell and disappeared.

I looked up. Back on Zone Two’s bridge, five men discharged a second spray of bolts over the swarm and lowered their crossbows to reload.

Bootfalls, military voices and lights played behind them in the tunnels. ‘Crossbows line bridges!’ someone boomed into the Hub. ‘Hold upper levels!’

My heart leapt as, across the bridge overhead, more men with crossbows filed out and lined the railings. Another troop armed with swords jogged from the tunnels after them in a blur of lantern lights. ‘Vortans to lower levels!’

Looking down, I saw Ghulzar haul himself back onto the arterial’s gills and start climbing again. Unarmed, legs streaked all bloody, the next Rath to reach him was caught by its shoulders and hurled into the open. The one behind it took a bolt from one of the crossbows in its back and went down after it. But Zone Three’s bridge was now crawling, the crossbow-fire merely picking at the edges of the crowd; a crowd that surged into a tight group as the men with swords made their way to the ladders and nets.

Above, on Two, a leading officer raised his lantern and gazed out at the walls of the chamber as if he stood in a bat cave in the moments before dark. ‘Drop your lights!’ he commanded.

Five lanterns fell. One hurtled past my head, another smashing on a pipe on its plummet to the water. I dared to watch the others, and the Rath that scattered out from them like angry termites—more than fifty around the water and among the laterals of Zone Six. More still rising.

‘Open fire on the climbers!’ A volley rained out on the Rath, just as a spear flew out of nowhere, right through the officer’s stomach. I looked away as he grunted, sword falling with a clang against his bridge and slipping off its side. I grabbed those railings as, in the corner of my eye, the officer’s body followed his sword down.

On the nets, bolts pierced the Rath fronting the crowd and delayed the rising of the tide. Some fell, I think, it was hard to see. Others, smitten, kept on climbing. Swords lunged. But even with Ghulzar gaining on my heels, I couldn’t move from where I was. Vortan soldiers were still streaming from the tunnel on Zone Two, blocking my way onto that bridge.

A white arm reached for Ghulzar’s boot; he rammed it down on the creature’s mouth, which pushed him higher. The chaser dropped and I heard its bones crack on the levers of the sub-gauge I’d never reached.

My mind spun back to the day I’d sealed Arte-III and stopped the flood. Arte-III still sealed, the lack of current was allowing the Rath up through its channel. Of course I knew that, I’d seen that. But the sub-valves . . . they divided pressure. Through the flow of jogging legs, I looked towards the tunnel exit. Then up, to darkness. The channel itself could only opened or closed at the mains. That was the floodgate. And I could open it again.

Unlawfully taken from Royal Road, this story should be reported if seen on Amazon.

‘Hold fire!’ shouted new command.

‘Vortans engage!’

Swords met the black spears and claws on the ropes above Zone Three. Ghulzar swore and shoved me upwards. ‘Enough overseein’ for a day!’ Blood from his nose coloured the dagger of his beard and goatee.

‘I have to get to the top!’ I shouted at him, clinging awkwardly from the railing so as not to be brushed off by the soldiers.

‘What for?’

‘If we open the mains we can flood them out again.’ I didn’t wait for his approval; just leaned out, buried my fingers back into the gills of the arterial and stepped clear of the bridge. I went on climbing. Past the crossbows on Zone Two, higher on the column of Arte-III, towards the ceiling. The vicious struggle of men and Rath fell farther and farther below, which helped me master the fear that was rolling through my stomach. I moved with purpose now—a plan—and had almost forgotten about Ghulzar when his hands brushed my soles.

‘That as fast as you go then?’ he brayed. ‘What are you—man or molerat?’

Spurred by his roar, I climbed faster. Saw the four great buttresses that converged around those vertical tubes. There were the arterial summits, their cresting girders and mains wheels.

I risked a glance down past my feet. Soldiers arriving from the access tunnels brought more lights; through their glare it looked as if the vortans had made it onto Zone Three’s bridge. The crossbows fired freely now, my heart lifting again at the screeches I could hear through the noise. And still more soldiers poured in, spanning the breadth of Zone Two to kneel a yard apart from each other until the whole bridge was covered. This had all happened too fast to have been Hetch’s doing. The High Commander must have believed me after all, and changed his mind!

Another shove from Ghulzar forced me back into my climb and my task, and he stayed behind me all the way to the top. At the summit, he wrapped his strong hands round my shins to hoist me up. I grabbed the mains wheel with one hand on the outer bar, almost slipping, but he caught me. ‘Steady!’ Gasping, I grabbed it with the other hand as well.

When I was sure of my balance, I made my way to the left side of the wheel. Ghulzar did the same on the right and there secured his footing. Closer snarls echoed up through the clashing and screaming, spitting crossbows, shouted orders. I willed myself to ignore them, nodded firmly and palmed the bar. We heaved together.

No give, no movement. Nothing at first.

Then—clank—the bar chugged towards me so sharply that Ghulzar had to lunge to grab my arm.

‘Keep on pushing,’ I urged him, regaining balance and pulling from higher up on the bar. He was doing the real work, I knew, but I couldn’t just hang there and watch. I locked my eyes on his big arms and bunching muscles; the rogue crossbow bolt that had pierced him in the shoulder under the brandmark, blood still running. The arterial’s workings began to grumble as we turned. The column shivered.

Officers below cried, ‘Narrow fire!’

‘Don’t let them climb!’

‘Fire on the walls!’

I tried to lean forward and look down, but Ghulzar growled me to attention with ice-blue eyes across the wheel. Arte-III’s vibrations filled our bodies, its rising moan drowning the cries below our perch. A rapid current filled the column, I could feel its power through the metal; a force too strong to swim against.

But I also heard the crossbow bolts that whistled closer under us. We didn’t have long. I kept on pulling at the bar, the shaking stronger all the time as the waking moan became a hiss.

Again that whistle, then a snap. A crossbow volley. When I felt something slip off the metal just below, I knew—they’d seen us. I held on tighter, the channel shaking against us. ‘It’s open!’ Ghulzar shouted.

I shook my head wildly. ‘All the way!’

‘Leave it, kid, man I mean it!’

The quaking jolted me down. I caught the wheel’s inner bar just as a white face loomed up and flung an arm towards my leg. Yelping, I kicked on instinct, while Ghulzar swung across the wheel. His boot missed it and, as he swung away again, the white jaws snapped. I kicked it harder this time and felt a tooth snag on my heel. And still I kicked, the panic adding to my strength I had to hope. At my second clumsy, grazing blow, the Rath dropped a short way but caught gills. Poising a spear, it hung there, waiting, glaring up.

The column shook with so much force we couldn’t keep hold of the bar. Ghulzar had climbed onto the gills above the axle of the mains wheel, and no sooner had I seen him than he reached for me as well. By my swathes, he hauled me up just as the Rath lunged for my feet. I fell over the metalsmith’s thigh.

The spear plunged.

If he cried out, I didn’t hear it over my own cry, but I saw him grab the ugly black shaft in both hands and break it off. Blood left his chest in two great spurts as he drove the broken end back down at his attacker. The Rath ducked it with a seemingly impossible movement. Readying to leap, its face distorted in a snarl that made its face look like a baby’s, wailing; chalk-white skin grooved deep with a beast’s rage. Ghulzar pressed his forearm to my neck and forced me back against Arte-III.

The creature leapt, caught him by the waist. Another one, from nowhere, took him by a leg and dragged him down. I batted after him, falling forward on the axle. My teeth chattered as it juddered through my body while, far below—past nets and bridges—soldiers with their lights had reached Zone Five! White water churned.

But Ghulzar was still here, swaying from his one-handed grip on the outer bar. Blood sheeted his stomach and legs and the heads of three Rath that dangled off him like white kelp. I watched him strain against their weight.

Two out of three leapt to his shoulders—that broke his grip. They shrank away, down through the Hub.

I yelled and punched the axle.

Ghulzar was gone.

Below, the battle on Zone Five was now a cauldron of churning. Arte-III’s floodgate was open. But two out of three sub-valves were closed, meaning that the ruptured segment was channelling almost all of the current we’d released. Could that hold?

As I thought it, two—three—six more Rath hopped into view not far below me. No one to fight for me this time. If I didn’t find a way to get off the arterial right now, then I’d be trapped here at the ceiling and they’d have me.

Something exploded. Far below, a massive rivet from a girder burst free and struck a vertical feeder. Water gushed out in a spout that broke the battle on the bridge, thrusting both men and Rath away. The girder had started to fail: from here I could even make out the row of jets shooting from its sides. If it collapsed, there’d be no way to flood the Rath out through its haemorrhage! My wrist was burning . . .

I glanced to the Ratheine climbers. One took a bolt in the back. It fell, taking another down behind it. But at least a dozen more of them coated the arterial’s sides, coming for me. I looked to the south wall: someone was yelling between the shots he was firing. Ammunition he was wasting to protect me, I knew: ‘Get out, boy! Out now!’ It was Plamen.

My wrist was burning . . .

Two of the climbers had been shot, but kept on climbing. Plamen lowered his crossbow and waved his free arm towards me. The Hub was now a storm of clashing steel, straining iron, churning water. And still the pressure must increase—I had to flush out any more and I could do it.

My wrist was on fire!

I hadn’t understood Plamen’s warning. The single Rath above me grabbed my swathes and hauled me up above the mains wheel—throat in its hands, face at its mouth!—beyond all range of crossbows at this height. Pulling against the monstrous strength of its arms, I ripped my swathes at the collar. That freed my neck and while white claws swiped to regain me, one of my swathe-frogs came unhooked. The cloak went loose. I dropped and, falling, struck the lever on my wrist.

The blaze broke free.

It whirled and swooped, lighting the ceiling—

—and vanished.

What, where? These weren’t the same gills.

A spout of water erupted. Still through the Sight, above me now, I saw the battle raging close. Right below, the roiling, churning, rising water of the flood. Rath in that water, still more coming. I was nowhere near the ceiling anymore, but all the way down on Zone Five, gripping the gills of Arte-I in a steady spray. The Disc had moved me! Again!

I jammed the lever, cut the Sight. Swathes gone, my hair and shirt were soaked, stuck to my skin. How had I even known to hold these gills?

No time for that. Arte-I was rocking with the pressure that I’d siphoned, while Arte-III had never stopped its massive quaking at the surge it couldn’t take. Its new girder was a ring of leaking fountains; the seething surface of the floodwater, rising fast, telling of the volumes being forced up through its second breach.

And still my wrist was burning.

The Rath were in their hundreds, thronging for the nets and scaling sides of bigger pipes to pick off soldiers. Vortans were hurled into the water, some by the Rath, some blown from ladders by the jets.

‘Fall back to the second bridge!’ shouted Plamen from somewhere in the madness. ‘Crossbows on the walls—only the walls!’ I spotted his white mantle as he ran across a higher bridge. It was a strangely distant thought that I was simply too far down to get out now; I’d die in here. But I could still increase that pressure.

I’d never get back up to the Mains, but just a little more strain on Arte-III from lower circuits might be enough to make the haemorrhage impassable. The sub-gauge of Arte-I was only a short distance above me. I climbed for it, squared up and pulled its levers out. Against my body, Arte-I’s vibrations went still and its row of leaks stopped altogether; while behind me Arte-III’s groan became a roar. I looked over my shoulder and saw it shake with such a force that Rath were thrown off its flanks.

Then its new girder cracked in half, more iron rivets shooting wide, white fonts of water bursting out. The green wall started to tremble.

And then the column was free-standing. Leaning away.

No, no, no, no . . .

‘It’s giving way!’ shouted Plamen. ‘Fall back! Back into the Deep!’ At his command, the soldiers turned and climbed and ran for closest tunnels. I watched through spray as, from the bridge where he was standing, Plamen met my eyes. ‘Leave the dead and fall back!’

The column buckled. My body seized and I cried out at the scream of tearing metal, then watched in frozen horror as its feeders snapped like twigs. Bodies fell through the shower of water and metal.

‘Look out!’

Another shape was coming down—a ceiling buttress. I threw myself flat between the gauge levers as the massive piece of ancient green masonry hit Zone Two’s bridge and broke the line of retreat. As it smashed through lesser laterals and plunged into the water, even huger iron rivets followed it down like metal hail. One split a rope net and sent a clutch of clinging Rath swinging across the Hub’s diameter like a long string of garlic. Arte-III groaned past the stone bridge by mere feet, then screeched its way down Zone Two’s bridge towards the webwork of cables at the centre, sure to snap or rip them clean out of their anchors.

Another rivet flew from somewhere, spinning straight towards my head, and struck Arte-I as I ducked.

Water blasted me clear—the rivet chased me as I fell.

I gripped my wrist.