The Sixth Sheet

The plan room had no windows and enough dust to make its own weather. I sneezed once over the threshold, which the clerk took as a sign I was not qualified to handle the papers.

“Gloves,” he said, setting a pair beside the ledger. “And nothing leaves this room.”

Ysabet signed us in. “We’re here to compare existing plans. No rubbing, tracing, or copying without approval.”

“I know the order,” I said.

“Then you know why I’m repeating it.”

Orren eased into the chair beside me. “Because she’s met engineers before.”

The clerk didn’t smile. He brought us a building plan of the Hall of Measures, two older surveys, and an index book with a cracked leather spine. The sheets were too large for the table, so we worked in sections, weighted at the corners with ceramic blocks the archive kept for that purpose. I put on the gloves. They dulled the small movements of my fingers, but the paper had survived longer than most people who handled it.

The first plan showed the Hall as it stood now: chambers, subcellars, service passages, and a shaded strip marking the oldest foundation. The seven-stone line we had sighted in the exposed wall lay under the central chamber, just as the building plan suggested. The drawing offered no reason for it to continue. Its east edge ended a few inches beyond the chamber’s wall.

“Could be a drawing limit,” Orren said.

“Could be an ending,” Ysabet replied. She held the plan flat without touching the ink. “We have to leave both options open.”

I checked the scale against the foundation measurements from the subcellar. It was imprecise, but the cuts on the exposed blocks matched the bearing. The line crossed the chamber and reached the east foundation. The plan did not show what happened after that.

The next survey was older, made before the Hall’s last major reconstruction. It used a different street datum and a different set of symbols. I searched for the foundation notation, then followed the line until it met a small block of rooms east of the Hall.

“Here,” I said.

Ysabet leaned in. “What am I looking at?”

“Lower Register. The old municipal records rooms.” I checked the key. “This label is for a foundation course, not a street or drain. The bearing carries through the Hall and under the Register.”

Orren ran a finger down the legend, stopping just short of the page. “That’s independent of the current building plan.”

“Same bearing, different survey,” I said. “Different draftsman, different scale. It’s not exact enough to put a point on a modern floor plan, but it’s enough to say the line doesn’t stop at the Hall.”