Su Wanyue, a medical officer from the underworld, discovers that the book of life and death has been tampered with after rescuing the souls of the dead. She joins forces with the mysterious Netherworld envoy Lu Chenyuan to fight against the "Netherworld Division", a supernatural organization that tamperes with reincarnation. In the process of solving a millennium conspiracy, she uncovers the truth that she fell into reincarnation as a doctor in her previous life after her husband died.
