The man at the counter was not the person Beorn needed.
"I'm here to see your guild master," Beorn said. "Tell him the protectorate's seat is calling."
The man worked through that statement step by step. First the title. Then the two guards positioned at the entrance. Then Aestrith, who had said nothing since they walked in.
He set the document he had been marking face-down on the counter and slipped through the door behind the shelves.
Beorn walked over to the sample table. Quarried stones lay arranged in a line across it, progressing from rough blocks to dressed pieces. At one end sat a bowl of lime, pale and finely milled, with a short wooden spade resting inside.
Three mortar samples sat beside it, each finished differently for comparison.
He pressed his thumb into the first sample, then the second, then the third. Each resisted with the same firmness. Nothing that told him where the guild might fail.
He picked up the lime bowl and rotated it slightly, studying the surface along the rim. The milling was even. He found nothing that concerned him and returned the bowl to its place.
The door behind the shelves opened.
The man who stepped through looked around sixty, perhaps a little younger. His build suggested he had spent years doing the labor himself before moving into management. His hands confirmed it.
The knuckles were broad and scarred, the skin rough past the wrists. He dressed simply, with no ornament or guild display.
He crossed into the room without ceremony. Before he had fully entered, his eyes had already mapped the scene. They stopped on Beorn standing at the sample table.
He noticed the lime bowl sitting half an inch out of place.
"Name's Cerdic," he said. "Guild master." He stopped at the counter's edge. "What brings the protectorate's seat here."
"A construction method I want to show you," Beorn said. "I need a private space and a few things from your stores. After the demonstration we can discuss what a working contract looks like."
"What kind of contract."
"Your guild provides the labor and the supply chain. I provide the process. The result is finished work nobody else in this territory can produce." Beorn kept his gaze. "The terms will be better than what you're currently operating under."
His expression was patient, a man who had heard offers before and expected them to fail under scrutiny.
"I've had three representatives walk through that door in the last years," he said. "None of them lasted long enough to matter."
"I know," Beorn said.
He let the statement stand. Cerdic waited for elaboration. None came.
Something in his eyes glimpsed as he finished judging.
"Back here," Cerdic said, already turning toward the rear passage.
The workroom behind the client hall had a lower ceiling. The air carried stone dust and the faint metallic warmth left behind by tools used earlier that morning.
A long bench ran along the far wall beneath a board where implements hung in careful order.
Two apprentices were fitting dressed stone when they heard the door. They looked up, glimpsed Cerdic's posture, and quickly found other tasks to focus on.
Beorn set the ledger on the bench. The charcoal came out.
Cerdic folded his arms. "What do you need."
"The room first," Beorn said. "Just us." He glanced toward Aestrith.
Cerdic's eyes moved between them. The silent woman. The ledger page marked during their walk through the building. The posture of the guards outside.
He took a moment with the conclusion he reached. If it was wrong, it was at least a reasonable guess given the circumstances.
"Supplies in the right-hand bins," he said. "Take what you need."
Then he walked back toward the client hall.
The storeroom was narrow. Shelves ran from floor to ceiling along both walls.
Raw stone blocks. Bags tied shut at the neck, labeled in chalk. Grit sealed in jars labeled by grade. Aggregate stored in open bins.
A cut high in the wall let in cold morning air and enough light to work.
Beorn set the lamp on the lowest shelf. He opened the ledger to the last written page. Then he stood still.
He already had the principle. The compound set harder when wet.
That much had surfaced before, during a thirty-second push that left a question mark in the margin. The working details had not followed.
Ratios. Mixing order. The full technical structure. Those sat on the other side of the fragments in his memory, clear somewhere, but inaccessible without effort.
He placed both palms flat against the edge of the shelf and pushed.
The headache arrived instantly. There was no gradual warning. One moment there was nothing. The next moment a tight pressure formed behind both eyes, complete and absolute.
He had learned not to treat that as a signal to stop.
Engineering knowledge always did this. Logistics came easily. When he asked for supply chain structures they assembled themselves. Administrative procedures surfaced intact.
Engineering resisted. It came through the fragments slowly, like something forced sideways through a space too narrow. The harder he pulled, the higher the cost.
He pulled harder.
The first thing that surfaced was the room where he had first encountered it. Rows of fixed seats. The dry smell of old paper and recycled air. A lecturer whose face he could not recall explaining why Roman infrastructure had outlasted everything built in the centuries that followed.
The explanation had been strategic.
Armies required supply lines. Supply lines required roads. Roads required bridges. Harbors required seawalls. Garrisons required construction that survived winter without needing to be rebuilt every spring.
Roman concrete came out of a military logistics problem. Armies needed roads that kept across seasons, harbors that could serve a fleet through winter without requiring reconstruction.
The formula was somewhere inside that memory. He located it and pushed again.
Volcanic material from geologically active regions. The type mattered, the composition. Reactive glass structure. Alumina content driving the binding reaction.
The right grade would be clear on inspection. Fine-milled powder. Grey-white with a faint warmth to the color. When pressed between fingers it clumped with defined resistance. Its smell carried a mineral heat nothing else in the storeroom matched.
He could recognize it when he found it.
Two parts ash to one part lime. The ratio arrived clean and exact.
Next came the mixing sequence. Dry components first. Combine them until the color is uniform. The volcanic powder goes in during this stage. Work it through before any water is added.
Water follows in stages. Add a portion. Work it completely through. Add the next portion. Repeat.
The proportions arrived with precise numbers, the kind produced by repeated testing.
Sweat had formed at his temples. His face had been running hot for the past two minutes. The headache had expanded from behind his eyes to the base of his skull, forming a tight band around his head.
He noted it and kept going.
The curing method surfaced last. Keep it wet for the first several days. The compound was hydraulic and gained strength from sustained moisture.
Fully cured, the material exceeded standard production by a margin that better aggregate or finer grinding could never reach.
He remembered reading about harbor walls built with this method that had remained submerged in seawater for over a thousand years while the concrete continued to harden. The reference had been in a military logistics text.
The argument had been simple. A harbor capable of serving a fleet indefinitely justified additional labor during construction.
Beorn lifted the charcoal and wrote before the knowledge could close again. Ratios went down the right margin in a narrow column, tight and legible. Identification notes for the ash beside them. Mixing sequence recorded in abbreviated notation.
At the bottom he wrote the curing instruction and boxed it.
He kept the entire record inside a margin-width strip that would not draw attention from anyone flipping through the ledger without knowing exactly what they were looking for.
His hand was shaking slightly. He finished the final line and stopped.
"You're red," Aestrith said behind him.
He did not turn. He reread the notes. "I know."
Silence followed. Then she asked, "How bad."
"Manageable."
He heard a subtle sigh behind him.
"Your hands were shaking," she said.
"They stopped."
She snorted in disbelief.
Beorn was silent for a moment, then looked over the materials. It was time to work.