Tang Yangyang unexpectedly inherits The Secret Arts of Profound Yin, a forbidden ancient book left behind by his grandfather. It records esoteric methods such as Qimen Dunjia and the Five Elements and Eight Trigrams, and also conceals the curse borne by the Tang family for generations.
When a neighbor, Auntie Wang, suffers from sleep paralysis, Tang Yangyang uses the book's "House-Pacifying, Spirit-Calming Talisman" for the first time and successfully drives away the evil spirit. This proves the book's authenticity and draws the attention of a mysterious woman named Xiaoyu.
Xiaoyu approaches Tang Yangyang under the guise of an antiques dealer, but seems to know a suspicious amount about The Secret Arts of Profound Yin. She displays unusual abilities while helping him deal with the Old Locust Tree Spirit, and the two become partners.
The pair are invited to Yunwu Village to investigate the "Wailing of a Hundred Ghosts at the Grave". They discover that the entire village is shrouded in ancient resentment, and that behind it lies a massacre of an entire family from seventy years ago and a mysterious bronze ghost mask.
As their investigation deepens, Tang Yangyang and Xiaoyu find that all these events seem to point to a much larger conspiracy, while Xiaoyu's true identity and motives grow increasingly suspicious.
