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 piece by piece. First the title. Then the two guards at the entrance. Then Aestrith, who had not spoken since they walked in.
He turned the document he had been marking face-down on the counter and disappeared through the door behind the shelves.
Beorn drifted toward the sample table.
Quarried stones lay in a line across it, progressing from rough blocks to dressed pieces. At one end sat a bowl of lime, pale and finely milled, 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 there hinted at weakness.
He picked up the lime bowl and turned it slightly, studying the surface along the rim. The milling was even. Satisfied, he set it back down.
A moment later the door behind the shelves opened.
The man who stepped through looked around sixty, perhaps a little younger. His build suggested years spent doing the labor himself before moving into management. His hands confirmed it.
Broad knuckles. Old scars. Rough skin past the wrists.
He wore plain clothes without ornament or guild display.
Crossing the room without ceremony, he took everything in before fully entering. His eyes stopped on Beorn at the sample table.
Then on the lime bowl sitting half an inch out of place.
"Name's Cerdic," he said. "Guild master."
He stopped at the counter, eyes still on the sample table.
"What does the protectorate's seat want with a masonry guild?"
"A construction method I want to show you," Beorn replied. "I need a private space and access to a few materials from your stores. After the demonstration we can discuss what a working contract looks like."
"What kind of contract?"
"Your guild provides labor and supply. I provide the process. The result is finished work nobody else in this territory can produce."
Beorn held his gaze.
"The terms will be better than what you're working under now."
Cerdic listened with a patient expression. He evaluated this as an ambitious offer, one that would probably collapse under inspection.
"You walk in under protectorate authority asking for supplies and closed doors, but you haven't told me what you're building, what it costs, or why this couldn't wait for a formal summons."
"A formal summons would waste time."
"That's not an answer."
"The method is the answer."
Cerdic rubbed a thumb across one scarred knuckle.
"Methods are easy to promise." His eyes flicked toward the lime bowl, still slightly displaced. "Results cost labor."
"Then let me show you results."
Beorn left it there.
Cerdic waited for more. When none came, something shifted behind his eyes as he finished weighing the exchange.
"Back here," he said, already turning toward the rear passage.
The workroom behind the client hall had a lower ceiling. Stone dust lingered in the air along with the faint metallic warmth left by tools used earlier that morning.
A long bench ran beneath a wall board where implements hung in careful order.
Two apprentices were fitting dressed stone when the door opened. They looked up, caught Cerdic's expression, and quickly found other tasks demanding their attention.
Beorn set the ledger on the bench and took out the charcoal.
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 guards outside.
He stood with the conclusion for a moment. If it was wrong, it was at least a reasonable guess.
"Supplies are in the right-hand bins," he said. "Take what you need."
Then he headed back toward the client hall.
The storeroom was narrow. Shelves climbed from floor to ceiling along both walls.
Raw stone blocks. Bags tied shut at the neck and marked in chalk. Grit sealed in jars by grade. Aggregate stored in open bins.
A narrow cut high in the wall let in cold morning air and enough light to work by.
Beorn set the lamp on the lowest shelf and 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 earlier during a thirty-second strain that left only a question mark in the margin. The rest had not followed.
Ratios. Mixing order. The full structure of the process.
Those remained buried somewhere beyond the fragments in his memory. Reachable, but only with effort.
He braced both palms against the shelf and pushed.
The headache struck instantly.
No warning. No gradual rise.
One moment there was nothing. The next, pressure locked itself behind both eyes, complete and absolute.
He had learned not to mistake that for a signal to stop.
Engineering knowledge always fought him this way. Logistics came easily. Supply chains assembled themselves. Administrative procedures surfaced whole and intact.
Engineering came slowly, like something being forced sideways through a gap too small to admit it. The harder he pulled, the greater the cost.
So he pulled harder.
The first thing that surfaced was the room where he had encountered it years ago. Rows of fixed seats. The dry smell of old paper and recycled air. A lecturer whose face he could no longer remember explaining why Roman infrastructure had outlasted nearly everything built in the centuries after it.
The explanation had been practical.
Armies needed supply lines. Supply lines needed roads. Roads needed bridges. Harbors needed seawalls. Garrisons needed structures that survived winter without being rebuilt every spring.
Roman concrete had come from a military problem.
The formula was somewhere inside that memory. He found it and pressed further.
Volcanic material from geologically active regions. The composition mattered. Reactive glass structure. Alumina driving the binding reaction.
The correct grade would stand out on inspection. Fine-milled powder. Grey-white with a faint warmth to the color. When pressed between the fingers it clumped with distinct resistance. Even its smell carried a mineral heat unlike anything else in the storeroom.
He would recognize it when he found it.
Two parts ash to one part lime.
The ratio surfaced cleanly.
Then came the mixing sequence. Dry components first. Blend until the color is even. Add the volcanic powder during this stage and work it through completely before introducing water.
Water came in stages afterward. Add part of it. Work it through. Add more. Repeat.
The measurements arrived with exactness, the kind born from repeated testing.
Sweat had formed at his temples. Heat flushed across his face. The headache had spread from behind his eyes to the base of his skull, tightening around his head like a band.
He noticed it and kept going.
The curing method surfaced last.
Keep it wet during the first several days. The compound was hydraulic. Sustained moisture increased its strength.
Fully cured, the material surpassed standard production by a margin finer grinding or better aggregate alone could never achieve.
He remembered reading about harbor walls built this way that had remained submerged in seawater for more than a thousand years while the concrete continued hardening. The reference had come from a military logistics text.
The reasoning behind it had been simple.
A harbor capable of serving a fleet indefinitely justified additional labor during construction.
Beorn picked up the charcoal and wrote before the knowledge could slip away again.
Ratios went down the right margin in a narrow column, tight and legible. Notes identifying the ash followed beside them. The mixing sequence went down in abbreviated notation.
At the bottom he wrote the curing instruction and boxed it.
The entire record fit inside a strip no wider than the margin, unlikely to draw notice from anyone turning through the ledger without knowing what to look for.
His hand shook slightly as he finished the final line.
Then he stopped.
"You're red," Aestrith said from behind him.
He did not turn. His eyes moved over the notes once more.
"I know."
Silence lingered.
"How bad?"
"Could be worse."
A quiet sigh came from behind him.
"Your hands were shaking."
"They stopped."
She snorted softly.
Beorn said nothing for a moment. Then he looked over the materials laid around the storeroom.
It was time to work.