Set in an alternate 2018 where Korea is a constitutional monarchy, Oh Sunny is a cheerful musical actress who suddenly becomes empress after marrying the emperor. Thrust into a world of secrets and power struggles, she finds herself caught in a web of palace intrigue and a mysterious murder that threatens the monarchy.

Determined to uncover the truth and find real happiness, she teams up with Na Wang Shik, a palace bodyguard with his own agenda. Na Wang Shik joined the imperial household seeking revenge on the person responsible for his mother's death. Together, they work to expose the dark secrets hidden within the royal family.