A clash of gunpowder-tech and the machineries of war leading to a showdown in steampunk Shanghai. Physician Jin Soling and Engineer Chen Chang-wei are stationed at a secret factory complex tasked with creating war machines. When a series of industrial accidents reveals an underground resistance, the two are faced with questions of loyalty, sacrifice and honor. Will they sacrifice their souls for the empire they have sworn to save? The third book in the Gunpowder Chronicles trilogy which started with Gunpowder Alchemy.