The smell of sulfur was still hanging in the kitchen entry when Imran stepped through the arch for his midday consultation. It wasn’t the clean, cold and exact scent of agricultural dusting powder he used in Yorkshire allotments, but the foul, choking reek of raw brimstone burned over an open coal pan. On the floor by the flour bin lay a pile of three hundred dead lantern beetles, their polished bronze back shells dull and curled inward like scorched walnut shells.
Sister Merrow sat on a low stool by the cold soup kettle, coughing into an apron powdered with flour and soot. Her eyes were red-rimmed. Across the room, Eren Tal was scrubbing the kitchen flat stone slabs with a bucket of hot vinegar and sand. The scrub brush made a harsh, scraping shriek against the wet stonework.
Imran didn’t put his tool kit down. He set his check magnifier on the table, pulled a clean handkerchief from his overalls. Then he held it briefly to his nose. ‘Who brought brimstone into a food preparation room?’
‘An apprentice from the College cleansing squad,’ Pella said, stepping out of the cellar doorway. She looked haggard, her fingers stained with black dark oak-ink and grease pencil smudge. ‘He came to the wicket gate an hour ago with a copper pan and three sulfur pellets. Said Master Sorell had authorized an emergency civic decontamination to protect the neighborhood from demonic vermin.’
‘And you let him burn it?’ Imran’s voice was uncharacteristically sharp, stripped of its usual calm Yorkshire cadences.
‘He threw the burning pan through the larder vent before we could drop the latch,’ Eren growled. It slammed his scrub brush into the bucket. Silt stench and vinegar foam splashed across his heavy work boots. ‘Tavi kicked the pan back out into the gutter with a shovel. But the smoke filled the cellar in thirty seconds. Look at the floor. Half the kitchen bread dough took the fumes. Merrow had to dump two tubs of sponge into the pig swill.’
Imran walked over to the pile of dead beetles. He knelt, took a wooden tongue depressor from his pocket. Then he gently spread the corpses apart. ‘Three hundred dead,’ he said quietly, counting the blackened shells. ‘All surface foragers. The workers and the breeding females in the deep mortar joints didn’t even notice. All the sulfur did was foul your sourdough crust, burn your lungs, and leave forty pounds of organic carrion inside your floor cavities.’
Sister Merrow looked up from her apron, her face pale. ‘Carrion? In the crawlway?’
‘What do you think happens to three thousand dead insects trapped behind a brick wall in a cellar running at ninety degrees Fahrenheit?’ Imran asked, looking directly at the old woman. ‘In seventy-two hours, bacterial decomposition sets in. You will have putrefaction gasses bubbling through the floorboards. You will attract blowflies, carpet beetles, and mold spores. The stench of rotting protein will drive you out of this kitchen faster than any river flood.’
He stood up, pointing with his depressor toward the wooden rafters above the larder. ‘And sulfur dioxide doesn’t fade into clean air like campfire smoke. It’s heavier than sky cold air. It settles into the floor joints, reacts with the surrounding water vapor from the river, and converts into rotten-egg acid. That acid condenses on every cool baked-clay pot, every flour sack, and every porous stone in your larder.’
‘Sister Merrow’s sourdough starter lives on airborne Saccharomyces cerevisiae spores,’ Imran added, his tone firm and measured. ‘Wild yeasts are exquisitely unsafe to sulfur dioxide. Commercial vintners use sulfur tablets specifically to kill wild strains before pitching lab yeast. If you allow sulfur smoke in this room, you kill her grandmother’s starter culture permanently. You won’t bake a leavened loaf in Lowbank for six months.’
Pella leaned against the bread table, rubbing her temples. ‘The college beadle told the street that beetles carry river plague. He said if we don’t allow a full brimstone purge tomorrow, the town council will condemn the whole block and order the building pulled down.’
‘Then the town council understands pest management about as well as they understand drainage,’ Imran said. He walked over to the large slate hanging on the wall, picked up a piece of chalk. Then he drew a simple cross-section of the kitchen foundation.
‘Listen to me carefully, all three of you,’ Imran began, tapping the slate. ‘Chemical eradication is the weapon of lazy technicians who don’t want to do the site work. If I came into a food processing plant in Leeds with a canister of broad-spectrum organophosphate or a sulfur burner, the health checker would have me jailed before nightfall. Why? Because poison doesn’t solve load-bearing problems. It merely redistributes the hazard.’
He sketched three arrows pointing from the deep soil toward the foundation. ‘First: water contamination. Your drinking well is forty yards from this cellar. Any water-soluble chemical you wash into these floor cracks will leach through the porous pipe lime and into the town water table within forty-eight hours. You will be drinking your own insecticide with your morning boiled tea.’
‘Second: food security,’ Imran continued, pointing toward Merrow’s storage jars. ‘Porous heavy clay absorbs sulfur dioxide. Your bread won’t rise because the airborne sulfur kills the natural wild yeast spores. You will starve your soup kitchen to kill bugs that weren’t harming your food in the first place.’
Eren wiped his forehead with his forearm, leaving a streak of gray mortar dust across his brow. ‘If we don’t kill them, Imran, they’ll keep coming. There must be fifty thousand of the things between here and the river wharf.’
‘Of course they’ll keep coming,’ Imran said evenly. ‘Because the ground beneath them is boiling. And that brings me to the third reason why chemical eradication is suicide: you’re killing your only tracking data.’
Pella looked up sharply. ‘Tracking data?’
‘Your monitoring instruments,’ Imran said, turning to her. ‘You don’t have electronic heat probes running into the deep drain tube chamber. You don’t have pressure transducers or remote tracking data lines. You have Eren’s ears, Ada’s single brass dial gauge, and these beetles.’
He reached into his pocket and placed the sample vial containing the live female beetle onto the slate ledge. The creature clung to the glass, its segmented antennae twitching toward the warmth of Imran’s palm.
‘These insects have evolved for ten thousand years to sense fractional heat variations in the river mud,’ Imran said. ‘Their nervous systems detect ground shakes and heat shifts long before your stonework shows a crack. If the drain tube upstream gets hotter, the beetles move ten feet farther south. If the pressure drops, they settle back into the riverbed.’
He tapped the glass vial with his knuckle. ‘The insects are your only working thermometers down here. You kill them, you walk blind.’
The room was quiet for a long moment. It was broken only by the steady drip of vinegar water from Eren’s scrub brush into the wooden bucket. Sister Merrow folded her apron back over her lap, her breathing slowing as the vinegar stopped the sulfur fumes in the air.
‘So what is the honest trade, Mr. Bell?’ Merrow asked, her voice raspy but calm. ‘If we can’t burn them, how do we keep them out of our flour bins without lying to our neighbors?’
‘We offer them a better cellar,’ Imran replied simply. ‘Insects don’t have malice. They have heat requirements. They’re crowding your flour store because it’s dark, dry, and forty degrees cooler than the crawlway floor. If we build them a padded, damp nesting gallery twenty feet away from your food stores—cooler than the floor, darker than the bins, lined with river moss—they will migrate into it voluntarily by midnight.’
Pella stared at the slate, her eyes tracing the foundation lines Imran had drawn. The logic was fully empty of mysticism, free of college cant. Then he entirely grounded in the physical reality of living things.
‘Heat relocation,’ Pella whispered. ‘Not an attack. A managed escape.’
‘Exactly,’ Imran said, checking his watch as the arch began its pre-departure chime. ‘Eren has sixty unglazed clay pot flowerpots in his timber yard. Tavi can gather damp moss from the weir wall. We line the pots, stack them in the cool north corner of the cellar, and create an artificial breeding hall.’
He picked up his light metal kit, stepped toward the shimmering oval, and looked back at Pella. ‘Tell Master Sorell’s apprentice that Lowbank doesn’t need his sulfur. We have an integrated pest management plan, and unlike his magic, it doesn’t leave poisoned bread behind.’
The arch flashed soft sapphire, Imran stepped through into the quiet Yorkshire afternoon. The washroom door latch rattled in the river wind.