Qin Ming, the King of the Underworld disguised as a beggar, descends from the mountains under his master's orders to find Bai Mingyu, a woman born with a Pure Yin constitution. He casually cures Bai Mingyu's father's terminal illness, forcing the cold and aloof female CEO Bai Mingyu to honor her promise to serve as his maid for half a month. Amid their daily bickering, Qin Ming repeatedly comes to her rescue, defeating a string of enemies, including Young Master Gu, the Black Dragon Society, wealthy businessmen from the provincial capital, and underground kingpin Master Gui. As his true identity as the King of the Underworld is revealed, affection gradually blossoms between them through their shared hardships. In the end, Qin Ming not only cures Bai Mingyu's chronic illness but also saves her family's business with his Mingqin Group, and the two lovers finally find their happily ever after.