Lin Xia, a mural conservator at the Dunhuang Caves, uncovers a Song dynasty layer and is swept away by mysterious Sanskrit writing into Chang'an on a blood-soaked night in the fourth year of the Zhenguan era. On the steps of the Yeting Palace, Li Shimin, the future emperor, holds a blade to her throat. A turtle-shell star chart glows cold blue in her palm: the very cipher that vanished from between the layers of a modern mural.
From convict slave to court official in the Imperial Treasure Bureau, she uses nanotechnology to restore a Persian gold casket and carbon dating to expose a false omen. But she discovers that every artifact she restores is changing the truth behind the “Mars Guarding the Heart” celestial case. A Western Regions score conceals a Turkic battle map, a nine-phoenix gold hairpin is coated in poison from a fallen dynasty, and the instruments of a modern archaeological team point toward Xuanwu Gate at the same moment as a sundial from a thousand years ago.
A gold-inlaid knife drifts down through the rift in time, slicing through the night. At last, Lin Xia understands the artisans’ cipher hidden deep within the mural, a message spanning a thousand years: only by bringing the lost Manual of Heavenly Craft back to light can she solve this deadly mystery tearing time and space apart.
