Zhang Wencai is a Hunyuan Mountain alchemist who has practiced with his master, Yan Chongli since his childhood. When Wencai is summoned to perform alchemy for the king in the palace, he accidentally discovers a demon who has been possessing people for some time. Although he attempts to capture it, it is far too powerful and Wencai only just manages to escape with his life. And so he heads back to enlist the help of his master...