The heat inside the junction chamber hit them like a wall of wet wool. Pella stopped five paces inside the arched entry. She lifted her lantern to shield her face from the dense fog that boiled off the floor. The chamber was twenty feet across, its circular walls built of massive blocks of mountain dark rock that cried streams of hot condensed moisture. Across the stone ceiling, thick stalactites of pipe lime and white chalk-stone had begun to form, some as thick as a man’s forearm, their tips dripping scalding stone broth into the dark swirl below.
In the center of the room sat the bronze collar. It was huge—a six-foot-tall casting of bell-bronze. Its greenish-gold surface glowed with an oily sheen under the lantern light. Four heavy iron clamping rings, each three inches thick and secured with square-headed nuts the size of a fist, bit directly into the antique baked-clay trunk. Where the metal crushed the green salt-glaze of the clay pipe, long white fracture lines spread across the clay pot like spiderwebs.
Eren waded forward, his boots splashing through four inches of steaming salt water. He stopped beside the nearest clamping ring, his eyes scanning the metal with a craftsman’s grim fury. ‘Look at the torque on those bolts. They didn’t even use lead thin wedges between the bronze and the baked-clay. Any apprentice carpenter knows that if you bolt iron directly to fired clay without a soft packing, the clay shatters the moment the heat jumps. They just cranked it down until it stopped turning.’
He reached out with a gloved finger, touching a raised circular emblem cast directly into the top curve of the bronze casting. The mark was clear: an open book surmounted by an eye enclosed in three nested binding circles. Beneath the emblem, deeply stamped into the metal with cold-punches, were four words in formal academy script: SEAL OF MASTER DAVIN SORELL. PROPERTY OF THE HIGH SUMMONERS’ SANCTUM.
‘Property of the Sanctum,’ Pella repeated, her voice flat and cold. She walked around the outer edge of the pipe hub, her measuring tongs held ready in her hand. ‘This isn’t an overflow bypass. This is an intake extraction pipe hub. Look at the upper branch.’
She pointed up into the shadows of the ceiling. A twelve-inch bronze sleeve ran vertically upward, piercing the dark rock vault through a roughly chiseled hole that had shattered the ancient keystone. Around the sleeve, bundles of heavy copper wire—thick as ship’s cables and bound in tarred silk—ran upward into the rock, pulsing with a pale, cold violet shimmer that made the hair on Pella’s arms stand on end.
Sister Merrow stood near the entry arch, her eyes fixed on the copper cables. Her jaw was set like an iron vise. ‘Binding lines,’ Merrow said, her voice dropping to a harsh whisper. ‘I saw those same lines used on the war-golems in the breach at Fort Gray. They’re extracting moving and elemental energy from the river current. They draw the water down from the high weir, spin it through a constriction throat to strip the pressure, and drain tube the raw magical deep ring up into the college towers.’
Pella drew out the Courtesy Bridge slate, laying the cool iron edge against the bronze pipe hub casing. The letters flickered into view behind the quartz window, sharp and unforgiving.
‘Fourteen hundred gallons a minute,’ Pella read aloud. Her breath hitched in her throat as she took in the figures. ‘And look at the fifth line, Eren. Grade IV extraction torcs. Master Sorell isn’t just cooling his lab fire. He’s running a forced extraction circle directly against the river body. He’s pulling raw elemental power out of the Gray Rush, using the river’s own high-pressure drop to compress the magic.’
She touched an animal fat candle stub to the upper pipe rim of the bronze pipe hub. The wax melted instantly, smoking with a sharp acrid hiss as it melted. Then he ran down the metal in white streams. ‘Surface heat is over eighty degrees,’ Pella observed, checking the melt rate against her counting pulse. ‘At this heat, the lead rubber rings between the valve plates will begin to flow under pressure. If a lead ring squeezes out, the high-pressure river current will cut through the bronze like an emery saw.’
‘And what does he do with the water once he’s stripped the magic out of it?’ Eren demanded, his voice rising above the dull roar of the pipe. He kicked the lower skirt of the bronze pipe hub with his heavy boot. ‘Look at the discharge elbow, Pella! Look where the waste goes!’
Pella lowered her lantern to the base of the collar. Beneath the bronze pipe hub, a massive bypass throat had been punched through the floor of the gallery. A pouring stream of boiling, foam-covered water was discharging through an unvalved opening directly into the low drainage channels that ran beneath the Lowbank apartments. The wastewater was bitter-salt, cloudy with dissolved lime, and steaming at nearly eighty degrees.
‘He dumps it here,’ Pella said, the realization settling into her ribs with the weight of cold lead. ‘He can’t return the boiling drain water to the upper basin. That was because the town water monitors on the Grand Canal would notice the heat right away. It would show up on the public gauges at City Hall. So he bored through the mountain rock and dumped the whole scalding mess into our drainage gallery. He’s using Lowbank as an open sewer for his engine.’
Eren pulled a scrap of chalk from his pocket and stepped to the wall. He marked the water level against the dark rock block—a crisp white line two inches above the current waterline. ‘If the river rises another foot at the spring tide, this chamber will be flooded to the vault. The boiling water will back up into the cellar drain pits, into the bakeries, into the drinking wells on St. Jude’s Lane. It will drown fifty families in their sleep, not with cold river mud, but with boiling chemical salt water.’
A sudden violent shudder rattled through the bronze pipe hub. The massive casting jumped an eighth of an inch on its iron footings, the turnbuckles groaning as the water hammer struck the inside baffles. A spray of boiling mist hissed from a hairline fracture in the lower baked-clay collar. It struck the dark rock wall with a wet splat that stripped the black algae clean off the stone in an instant.
‘Out,’ Sister Merrow commanded, her cane striking the wet floor like a gavel. ‘We’ve seen what we came to see. That joint is on the verge of blowing its packing. If that bronze sleeve shifts another quarter-inch, this entire chamber will fill with live steam in thirty seconds. Move, both of you!’
Pella knelt beside the hot baked-clay trunk. She ignored the steam that singed the wool of her apron bib. She pulled out three clean sheets of heavy rag paper and a lump of soft graphite. She pressed the paper firmly against the stamped stone carving on the bronze casting. She rubbed the graphite over the raised lettering with swift, firm strokes. The impression came through dark and precise. The College crest, Sorell’s personal signet, and the manufacturer’s foundry date stamped three weeks ago.
‘Got it,’ she said. She folded the sheets into an oilskin wrapper. Then she tucked them deep inside her tunic against her ribs. ‘This isn’t ancient salvage. This casting was poured last month at the High Tor Foundry. It’s fresh work. Sorell can’t claim it was left here by the old town water board.’
Eren fitted his six-inch iron wrench to the lowest clamping nut, bracing his boot against the stone floor pad. He didn’t turn it—he simply applied ten pounds of sideways push to test the bolt’s stretch. The forged iron gave with a soft, spongy creep that made him grimace. ‘Threads are yielding,’ Eren muttered, tapping the nut with his knuckles. ‘The heat has heat-softened the iron. It’s lost its temper. If anyone tries to tighten these clamps to stop the steam leak, the studs will shear clean off. This whole pipe hub is sitting on borrowed seconds.’
Pella pulled her brass line-weight bob from her apron pocket, suspending the weighted pear on three feet of waxed string over the baked-clay pipe. The brass bob didn’t hang straight down. It danced in tight, wild circles. It shook with a high-hum sky-high hum that proved the baked-clay trunk was undergoing severe internal bubbling blast. ‘The water inside is boiling at cold river heat because of the empty pocket,’ she noted, her pencil flying over the back of her graphite rubbing. ‘The bubbles are collapsing against the pipe wall like tiny hammers. Ada described this in her heating books. It’s pitting the clay from the inside out.’
They pulled back down the Gallery of the Three Oars, their boots throwing up sheets of warm, rotten-egg water as they hurried toward the distant square of gray light that marked the cellar hatch. Behind them, the deep, clockwork hum of the drain tube pipe hub seemed to follow them. It echoed through the bowed oak balks and shook the ancient brick vaults.
As Pella reached the bottom of the ash ladder, she looked up. At the top of the hatch, framed against the kitchen cellar ceiling, Tavi was leaning over with wild eyes. He pulled the rope line twice.
‘Pella! Eren!’ the boy shouted down, his voice cracking with terror. ‘Come up! The High College court guards are at the kitchen door! They’ve got four armored guards and a wooden relic crate!’