The noon horn from the Summoners’ College sounded across the valley of Lathmere, a high, clear, brassy note that drifted down through the river fog like the call of a hunting bird. It was answered, three seconds later, by the deep, iron clatter of the Lowbank ferry bell signaling the midday change of wagon drivers.
Inside the back kitchen larder, Eren Tal spat on his palms. He set his boots six inches apart on the damp flat stone slabs. Then it raised the five-pound forged steel sledge hammer to his right shoulder.
Pella knelt three feet back. She held the brass-hooded oil lantern with both hands, her back pressed against the pickling shelves. The flame inside the glass chimney flickered yellow and steady, feeding on clean colza oil, throwing long, jittery shadows across the rough limestone blocks framed between the two oak shores.
“First strike is on the keycourse,” Eren said. His voice dropped into that calm, clockwork rhythm he used when splitting a seasoned log of heart-elm. “I’m going to take the corner stone right at the floorline. If the mortar shatters clean, the stones above will bridge across the oak. If it crumbles like sand, hold your lantern high and watch for water.”
“I’m watching,” Pella said.
Eren set the one-inch cold chisel into the level mortar joint at the base of the central block. He held the eight-sided steel tool with his left hand, his knuckle wrapped in a strip of greasy leather to protect against an off-center blow.
He swung the sledge.
The impact rang like a blacksmith’s anvil in the cramped larder. The blast wave rattled the glass chimney of Pella’s lantern and shook through the soles of her boots. A two-inch scab of white lime mortar burst from the joint, spitting powdery white dust across Eren’s leather apron.
He didn’t pause. He struck again.
The chisel bit two inches into the joint. A hairline crack zigzagged upward through the limestone block, parting the stone along a natural rock layer seam.
Eren dropped the hammer, took the six-foot ash lever bar. Then it jammed its chisel-point into the widened crack. He threw his whole weight onto the lever, his shoulders bunching under his woolen vest, his heels digging into the flat stone slabs.
With a wet, sucking sound, the four-hundred-pound limestone block groaned, tore free from its ancient lime bed. Then it slid forward two inches onto the floor.
“Catch the dust,” Eren grunted.
Pella leaned forward with her lantern.
Through the two-inch gap where the stone had moved, a sudden draft of air puffed out into the larder. It wasn’t the cold, clean autumn air of Lowbank. It was hot, thick, and suffocatingly humid. He carried the distinct, bitter-salt stench of boiled lime and the decaying, sweetish smell of rotting river silt.
The flame inside Pella’s lantern didn’t just flicker. It flared dull orange, stretched into a thin, smoking thread of soot, and suddenly died.
The larder went pitch black.
“Hold,” Eren’s voice came out of the dark, instantly still, fully empty of panic. He didn’t drop the bar. “Don’t move your feet, Pella. Did you smell that?”
“Yes,” Pella whispered, her eyes straining against the total blackness. Her heart was beating against her ribs like a trapped bird.
In the sudden absence of the lantern light, the sound from behind the wall filled the small room.
It wasn’t silence. It was a vast, hollow, echoing breath.
From the black void behind the displaced stone came a deep, rhythmic, clockwork pulse. The sound of thousands of gallons of water rushing through an enclosed underground throat, with the high, singing hiss of trapped air escaping through a pinhole under huge pressure.
A low hiss followed by a heavy high-pressure thump. Over and over.
It sounded like the breathing of a huge, wounded beast trapped in a granite cellar beneath the city.
“Bad air,” Eren said calmly. His hand found her shoulder in the dark, his grip heavy and steadying. “The flame didn’t blow out from a gust, Pella. It starved. There’s no oxygen in that gallery. Just damp cold air, sulfur vapor, and whatever gas is boiling off that hot mud.”
“My father’s bypass,” Pella breathed. Her hand reached out through the dark until her knuckles touched the cold, wet face of the displaced limestone. The stone was dripping with hot water drops, warm as freshly drawn milk. “He didn’t seal this gallery fourteen years ago because it was empty. He sealed it because it was full of bad air from the river intakes.”
A sharp, clear chime echoed from the washroom behind them.
The courtesy arch had activated.
A warm, amber light spilled through the larder doorway. It cast long, box-shaped beams across the floor, lighting up the dust motes hanging thick in the disturbed air. Inside the oval, framed by the turquoise-crusted brass ring, stood Ada Morland, wearing her bright orange boiler suit, her steel-toed boots planted squarely on the rubber mat, her canvas tool tote gripped in her left hand, and half an egg-and-cress sandwich held in her right.
She stopped in the doorway, her sharp, experienced eyes taking in the oak shores, the displaced limestone block, the put out lantern, and the gray mist curling out from the crack near the floor.
“Well,” Ada said, her voice cutting through the hollow hiss of the gallery like a cold brass chisel through rotten lead. “I see you two have been playing with the stonework without checking the air-flow.”
She took a bite of her sandwich, chewed step by step for three seconds. Then she pointed with her crust toward the put out lamp in Pella’s hand.
“Put the matches away, girl,” Ada instructed, stepping forward into the larder. “If you strike a sulfur match in front of an unvented sewer gallery, you won’t need to worry about the Summoners’ College. You’ll just arrive on the High Terraces in three separate pieces.”
Ada set her canvas tote down on an empty pickling crock. She pulled a small brass check mirror and a flat grease pencil from her pocket. Then she knelt by the displaced stone.
“Feel that draft on your knuckles?” Ada asked, gesturing for Pella to put her hand by the gap. “It’s pulling out, not in. The void is under positive pressure. That means whatever is venting into that tunnel upstream is blowing steam or trapped air faster than the ground can absorb it.”
“Can we go in?” Eren asked.
“Not unless you fancy waking up with your lungs full of cold air and your tongue swollen like a boiled turnip,” Ada replied crisply. “We ventilate first. Bellows, canvas chutes, and a rolling candle trolley. You don’t put a boot in a hole until a candle can burn at the forty-foot mark for ten minutes without sputtering. That’s rule one of drainage.”
Ada knelt beside the breach, her bright orange boiler suit bright against the soot-blackened stones of the larder floor. She took her four-inch brass drift and tapped the edge of the limestone block Eren had just moved.
“Solid stone,” Ada observed, her fingers inspecting the rough fracture. “River limestone. Good crushing strength, terrible shear pushback. If you hit this stuff with high pressure from behind, it doesn’t bend. It pops like a dried pea.”
She took her brass check mirror—a polished three-inch disc mounted on a swiveling copper handle—and held it inside the two-inch breach. She held a small animal fat candle near the glass, angling the glow into the dark void beyond.
“Look at the water drops on the mirror,” she said, pulling it back.
The polished brass surface was instantly coated in a dense, greasy film of gray moisture that didn’t run off like clean water. It clung to the metal in thick, cloudy beads that smelled sharply of hydrogen sulfide and rotten canal weed.
“That’s stone steam,” Ada diagnosed. “It’s boiling off an open channel somewhere within fifty feet of this wall. And feel the air draft.”
She held a strip of light cotton thread near the gap. The thread blew straight back toward the larder, fluttering wildly at a forty-five-degree angle.
“Positive pressure,” Eren remarked, leaning on his sledge.
“Positive pressure and ninety percent humidity,” Ada said. She stood up and brushing the white lime dust from her knees. “Which means whatever is leaking into that gallery isn’t just a cracked pipe. It’s a high-pressure discharge. If you had knocked that whole wall down with a sledgehammer, you’d have filled this entire back kitchen with sulfur gas before you could find the exit.”
She reached into her canvas tote, pulled out her padded thermos, unscrewed the cup. Then she poured out three ounces of thick, steaming lentil soup.
“First rule of confined space entry,” Ada said, taking a slow sip. “You don’t enter until you have cross-air-flow. You need a blower, a wind-tube, and an exhaust route. And you don’t send a human being into a hole until a candle can burn at the bottom for twenty minutes without turning blue.”
She looked at Pella. Her keen blue eyes took in the apprentice’s scraped knuckles and soot-stained cheeks.
“You did the right thing stopping when the lamp died,” Ada said. Her voice dropped into a rare note of genuine test. “An idiot would have lit another match and walked into the dark. A tradesperson stops, takes a breath, and figures out why the light went out.”
She handed her empty soup cup to Pella.
“Ten minutes left on my lunch break,” Ada said. “Let’s draw up the air-flow plan before my countdown hits zero.”
She looked at her wristwatch, swallowed her bite of sandwich, and tapped the stone with her brass drift.
“Twenty-two minutes left on my lunch break,” Ada said. “Let’s see what else you’ve shaken loose.”