To find her missing father, Bai Ling journeys to the Qinling Mountains with Zhao Yan, Gu San, and five other companions. They unexpectedly enter the underwater underground palace of the White King. Built by the White King, a subordinate of Shi Le during the Sixteen Kingdoms period, the palace is filled with sophisticated mechanisms and layers of defenses, including quicksand passages, floating-stone walkways, and rotating labyrinths. The waters inside the caves form a self-contained ecosystem inhabited by colonies of ants, aquatic reptiles, giant crocodiles, and other native creatures. The team's intrusion disrupts the ecological balance, forcing them to solve deadly mechanisms and fend off attacks from subterranean creatures. In the main burial chamber, they discover the White King's confession written on silk, uncovering secrets about Shi Le and the Nine Kings that have remained buried for a thousand years. This AI-original adventure story features mysterious phenomena caused entirely by geological formations and man-made mechanisms, without any elements of superstition.