The green silence of the stone-hard canopies did not end with an archway or a sudden clouded eye. It dissolved slowly, grain by grain, into an air dried by underground drafts and scoured of vegetal sweetness. Where the last hardened roots of the Verdant Vaults narrowed into black shale, the living rock had been planed flat by heavy iron chisels, squared into massive lintels, and faced with heavy plates of dark, unpolished pig iron.
Qiao Ming paused upon the final ledge of stone-hard wood, his bare calloused feet testing the sudden change in heat. The andesite flat stone slabs beneath his heels were cool and damp, holding the memory of ancient sap, but the iron threshold before him was dry as kiln brick. It drew the natural moisture from his soles with a hungry, metal cling. He hitched his oilskin coat tighter across his broad shoulders, feeling the sixty-fathom coiled horsehair line shift against his collarbone.
Behind him, Yan Zhiqiu stood with both hands pressed against the Broken Slate, her dark eyes reflecting the faint, coppery sheen of the hall ahead. Her boots made no sound against the shale, but her breathing was shallow, attentive to the sudden change in sound timbre. The hollow, echoing boom of the tidal surge that had accompanied them through the high green chambers had flattened into an endless, low-hum drone. An underground hum shaking through the bedrock like an iron string plucked twelve hundred years ago.
