Gu and Sella crawled along the south tunnel with a brass probe and chalk. The passage was low enough that Yan had to duck even before he reached the first fork. He carried the brace bundle and stayed behind them while they tested the brick.
At the fork, a capped route followed Gu’s original drawing. The active branch left it through a newer joint and sloped toward the lower road.
Sella rubbed the metal sleeve with her thumb. “This came from the Registry after you left.” She checked the date against her maintenance book. “The station received no notice of an extension.”
Gu examined the capped line. “My plan ends here. This doesn’t.”
They followed the branch until the tunnel narrowed beneath a stone foundation. A faint draft carried voices from beyond the wall. No house appeared on the current map.
Han raised a hand. “We stop here. We survey the structure before we open anything.”
Yan set down the braces. “I can hold the passage if the stones shift.”
“The supports need timber and wedges, not a strong back,” Sella said. “We’ll get the carpenter.”
