In 1939, Shanghai, now under occupation, is rife with hidden currents. Su Jingming, the military procurement commissioner, colludes with the Japanese, using the underground works beneath his mansion to conduct secret dealings. The city’s many factions are entangled in a fierce struggle for power. Shen Yan, an underground agent, assumes the identity of Su Wanqing, a fallen young heiress, and infiltrates the Su household as the fifth concubine. While weathering the probing scrutiny of the wives, concubines, and steward, she secretly rallies those in the household who are willing to resist. Caught between collaborationist agents and the spies of rival factions, she waits for a chance to uncover the enemy’s core conspiracy, carrying out her undercover mission on a battlefield where no shots are fired within the walls of the mansion.
