The mark in the threshold of Entry hall 126 was clear.
Qiao Ming knelt on the narrow dark rock curb that divided the weeping crypt from the transitional hall leading to Master Mason Lu’s stone base. The floor here was dry, covered by a thin, brittle crust of salt-frost that had formed where the cold drafts of the lower chimney pipes met the humid air of the hypogeum. The frost was delicate, crystal-clear like frozen spiderwebs, preserving every disturbance with total fidelity.
Directly across the threshold stone, cutting cleanly through the white frost, was a fresh, sharp scratch.
It wasn’t the wide, rounded scrape left by a stone-boat’s runner or the jagged gouge of a falling stalactite. It was a three-sided clean cut, barely a line wide and nearly a tiny fraction of an inch deep, chiseled into the hard dark rock flag with razor-sharp, diamond-hard care.
Qiao Ming lowered his horn lantern until the flame was an inch from the stone.
He drew his bone-awl from his harness and carefully probed the groove. The clean cut had been made by an iron tool with an extremely acute edge—an instrument of refined, royal steel forged in the high workshops of the Obsidian Scroll hall. At the bottom of the trench, pressed into the crushed rock powder, lay a tiny crumb of yellow beeswax mixed with ground red stone.
