The Prince of Yan Kingdom, Yu Fei Chen, marries the daughter of the general who controls the country, Yin Nan Yao... or so everyone thinks. The bride he gets is actually Yue Ji An, an assassin from a secret organization sent to claim his life.
But the Prince is not all he appears to be either; he is an undercover agent who works to expose the criminals and punish the unrighteous.

As these two play their games around each other and get to know each other, Yue Ji An finds herself becoming more and more reluctant to kill Yu Fei Chen. Likewise Yu Fei Chen, with his dual identity and a overarching view of the whole situation, is increasingly reluctant to expose this "substitute bride" he has come to care for.