The play is adapted based on Guoguo's novel of the same name. Big Demon Qi Fengyin (acted by Li Hongyi), born out of evil thoughts, is locked in the Panic Mountain Barrier due to his killing of the mortals and immortals a thousand years ago. The small Medicine Spirit Yamao (acted by Sun Zhenni), transformed from the herb Huanyangcao, is chased by all sorts of people due to its magic physique and happens to break in the barrier, leading Qi Fengyin's failure to have a human body and his evil thoughts fly. Since then, the two have had a deep bond and have experienced all kinds of stories together.