Bai Yin Qi is the King of Sumeru. He is handsome and intelligent, but his strengths are of no use in an imperial court controlled by corrupt officials. Assassins come and go, but one day, he falls in love with female assassin Yu Yan. Because of another assassination attempt wherein his loyal guard Tian Xiao Li risks his life to save the King along with a mysterious pocket watch, the three time travel to the year 2018.