The queen of the human tribe gives birth to twin daughters. The elder sister, Qing Kui, is kind and beloved, promised to the heavenly prince. The younger, Ye Tan, clever but misunderstood, is set to marry the demon prince. But a twist of fate leads to the sisters being wed to the wrong grooms. What begins as a mix-up unfolds into two unexpected love stories — and a brewing conspiracy that threatens to upend all four realms.