The drain in the north wall was four feet high and three feet wide. Centuries of running water had left ridges of lime on the black stone. Cypress roots hung over the entrance like wet rope, and silt had collected at the foot of the opening.
Pei Jing pushed the roots apart and went in headfirst, dragging his pack. Once he was through, he reached back and let the roots fall into place. The air was colder on the other side. Water dripped from the ceiling into a shallow stream running down the floor. It smelled of rust and old moss.
He went forward in a low crouch, using the Shadow-Stepping Stance the night runners of the Southern Reach had taught themselves. He kept his weight on the fronts of his feet and followed the running water. The stream covered what little sound his boots made.
His fingers brushed the right wall every few paces. A shallow slash and two little pricks broke the crust of lime. Ten paces on, he found another set. Gui had cut the marks by hand with a fine scribe, leaving no qi behind. Someone who didn’t know to feel for them would take them for cracks.
