The kitchen larder smelled of spilled rye flour, damp limestone. The quiet sourness of yeast starters that had rested in stone crocks since before the autumn rains. But beneath the familiar domestic aroma, Imran Bell smelled something that didn’t belong in a food store. The dry, bitter-salt heat of baked mortar, the faint pine-scented odor of scorched beetle back shells. The clear silt stench rising through the foundation joints from the riverbed below.
He knelt on one knee in the white drift of flour, his thick cotton overalls stretching over his shins. In his right hand he held a plain camel-hair brush, its bristles no wider than a pencil eraser, and in his left he held an unsealed glass sample tube with a push-fit cork. He didn’t move his feet. A good exterminator learned in his first month that walking through an active infestation before reading the floor was the surest way to destroy forty percent of your evidence.
Across the doorway, Pella Rook and Sister Merrow watched him in utter silence. Merrow held an unlit candle in a brass dish, her apron dusted with gray flour and flaking pipe lime. Meanwhile, Pella leaned against the door post with a pine drafting board tucked beneath her arm. Outside in the main back kitchen, the kettle was singing its customary low note of boiled tea. Meanwhile, Eren Tal’s adze struck dry oak in the wheelwright yard with a steady, rhythmic thwack.
Imran lowered his face to within four inches of the flat stone slabs. The insects were not running in uneven circles like roaches caught beneath an overturned sink. They were marching in tight, deliberate columns three inches wide, their polished black wing-cases clicking against the stone with a sound like dry lentils rolling down a copper chute.
‘They’re not feeding on the rye,’ Imran said quietly. That kept his voice level so as not to startle the column. ‘If they were feeding, you’d see feeding scars along the sack hemp and masticated meal around their palps. Their jaws are fully clean.’
He lifted the brush, gently nudging a three-quarter-inch adult from the rim of a split sack. The insect didn’t snap its jaws or try to burrow into the grain. It simply walked up the camel hair toward the glass vial, its long, segmented antennae sweeping the air in wild arcs. Imran tipped the tube. That let the beetle slide down the smooth inside wall, and pressed the cork into place.
‘Look at the antennae under the glass,’ Imran said. He held the vial toward the doorway where the morning light entered from the alley. ‘The end-post clubs are singed. That’s third-degree heat black rot on the sense hairs. They didn’t come in here looking for breakfast. They ran up out of the sub-floor because the channels below are roasting them alive.’
Pella stepped into the larder, her boots crunching lightly on the spilled meal. She reached into her canvas satchel and produced a stick of blue chalk, a set of grease pencils, and a folded sheet of rag paper. ‘The cellar below this floor houses the old river bypass water chute Hal Rook built thirty years ago. Does the heat line follow the pipe?’
Imran reached into his pocket and drew out his bimetallic surface probe. A clean, brass-stemmed heat gauge with a circular dial face shielded by heavy stone crystal. He pressed the flat copper foot of the instrument against the center of a wide granite flat stone slab. The black needle quivered, creeping slowly upward until it settled at eighteen degrees.
‘Eighteen degrees on the stone face,’ Imran said. ‘Normal surrounding for an unheated stone pantry in late winter.’
He lifted the probe, shifted it four inches to the left. Then he pressed the copper foot directly into the soft lime mortar joint between the two slabs. The needle didn’t creep. It jumped.
Within five seconds, the pointer swept past twenty-five, passed thirty, crossed thirty-five. Then he struck forty-one degrees before shuddering to a halt at forty-three point eight. The mortar was hot to the touch, venting a thin, almost invisible shimmer of dry heat into the dust.
‘Forty-three point eight,’ Imran murmured, reading the scale with practiced care. ‘Over one hundred and ten degrees Fahrenheit. You could incubate quail eggs in that crack. No cold-blooded detritivore can survive in an enclosed stonework channel at that heat. Their beast-blood begins to desiccate within twenty minutes.’
Sister Merrow crossed her arms, her knuckles white against her dark apron. ‘The College beadle told the market wardens that these things were demon vermin spawned by the river filth to poison the poor folk’s bread. He wanted to throw sulfur cakes down the chimney pipes.’
‘If you throw sulfur down those chimney pipes,’ Imran said. He looked up with a hard, flat stare, ‘you will convert that forty-degree lime mortar into calcium sulfate and generate sulfur dioxide gas that will fill every tenement cellar within two blocks. And you wouldn’t kill the beetles. You’d just force them through the chimney pipes into the sleeping rooms upstairs.’
He moved six feet further along the wall, placing the probe on three successive mortar joints. At each seam, the heat read between thirty-nine and forty-four degrees. When he reached the far western corner. There, the floor met the outside river foundation, the needle dropped suddenly back to sixteen.
‘The heat slope isn’t uniform,’ Imran observed. It pulled a red grease pencil from behind his ear to sketch the isotherm contours directly onto the whitewashed wall. ‘It forms a sharp, linear wedge. Whatever is cooking the ground underneath us is running in a narrow, high-pressure hall straight beneath this pantry.’
Pella unrolled her foundation map on top of an empty flour barrel, weighting the corners with dark oak-ink bottles and lead sinkers. ‘That hall matches the backup drain tube intake Ada identified two days ago. Sorell’s team has high-pressure the underground line. The heat is bleeding directly into our footings.’
Imran dipped his camel-hair brush into a shallow saucer of clean river water and washed the dust from the glass dial of his probe. ‘Well, your summoner friend may be an expert in sky shape. But he doesn’t know the first rule of heat shifted weight. When you run boiling pipes under cold stonework, the earth expands. And the first living things to feel that spreading aren’t the inspectors on the High Terrace. It’s the creatures living in the cracks.’
He picked up three more adult beetles, placing them in separate sample jars with punched holes in tin lids. Each insect moved with a matching, purposeful gait, heading toward the coolest corner of the jar.
‘Notice their orientation,’ Imran said, tapping the glass with a thumbnail. ‘Every single worker is facing away from the mortar line. They aren’t lost, and they aren’t swarming. They’re executing an organized living retreat.’
Outside, the rain began to fall again, beating a hollow rhythm against the wet stonework of the river wharf. Through the larder window, the grey towers of the High Terrace looked cold, distant, and fully unaware of the underground pressure building beneath their foundations.
Sister Merrow bent down and picked up a scrap of fresh sourdough crust that had fallen from her morning tray, tossing it into a waste bin. ‘If they aren’t eating the grain, what are they living on down there?’
‘River lichen and organic silt,’ Imran explained, gesturing toward the floor. ‘These beetles are detritus processors. They break down the river sludge that would otherwise clog the stone weeping channels beneath your quay. Kill this colony, and within six months your cellar drains will choke with black mold and rotting sedge grass.’
He ran his thumb over the brass dial housing, checking the seal around the crystal bezel. In Harrowby, a checker who dropped his main instrument on a concrete floor was docked half a week’s wages. Imran had carried this particular gauge through four hundred town basements without cracking the glass. Its fine-tuning had never failed him.
Pella leaned over the barrel, watching the red grease pencil line extend toward the threshold. ‘Hal Rook used to say that the foundation of Lowbank wasn’t stone, but balance. If one arch gives way, three cellars drown. If the river beetles are boiling, how long before the mortar turns back into sand?’
‘Mortar made with high-pressure lime begins losing solid strength at sixty degrees under nonstop soaked steam,’ Imran answered, his tone cold and exact and detached. ‘You’ve got forty-three degrees right now. At forty-eight, the bond breaks down into slurry. At fifty-five, the stones settle into the bedding mud.’
He stood up, wiping the flour from his knees with both palms. ‘We have about six hours before the heat in that mortar reaches fifty degrees. At fifty degrees, the larvae inside those walls will begin to cook in their shells, and when that happens, the adults will go berserk trying to carry them into the street.’
Pella looked down at the thousands of glistening black shells moving steadily across the floor. ‘What do we need to do, Imran?’
‘We don’t kill them,’ Imran replied, snapping his sample kit shut. ‘We give them an escape route that leads somewhere cold. If you give an insect an exit, it will take it every single time.’