Three-and-a-half-year-old little beggar Jiang Xiaoman possesses a peculiar sense of smell, able to smell lies, poisons, and near-death breath. Amidst a snowy night, mother Liu Qingheng is afflicted with a strange poison and is in critical condition, while the medicine money is snatched away by someone. Driven to desperation, Xiaoman hugs the leg of the Prince Regent Pei Yan—who holds supreme power over the court and is dubbed the "Living Yama"—right on the street, and blurts out a cry of father. To exchange for life-saving medicine, Xiaoman is forced to rely on her talent to help Pei Yan successively crack fatal plots. As one crisis after another is uncovered, the old case of the General Defending the West from seven years ago surfaces, and half a gilded longevity lock implicates a startling birth background.