In Korea’s feudal past, the deposed Crown Prince Lee Heon has been forced into a lonely exile by his cruel older brother, who has usurped the throne. Lee Heon fears for his life at every moment, as his brother plans to secure his place on the royal seat by killing him. Assassins and other schemes are a constant threat for Lee Heon, whose only true ally is his faithful and kind-hearted bodyguard Geum. Meanwhile, in modern times, a high school student named Eun Ho loves paintings. In fact, art is his whole world. And when he is tasked with completing a mysterious painting, he is unexpectedly drawn back into the distant past, where he meets Lee Heon. The duo starts to form a close, romantic, and tender bond. But as the acting king grows restless, hoping to kill the exiled Crown Prince as soon as possible, Eun Ho begins to understand that he may be Lee Heon’s best – or perhaps only – chance of survival...

Liu Xiang Ciang had a dream where she was in Kingdom of Chu and became assassin, and had four opportunities to assassinate the prince Mu Chun Shen. If she failed, she was poisoned to death. In order to complete the assassination mission, she turned into a maid, a guard, and a beggar boy in the prince's mansion. Every time the assassination was about to succeed, there would be unexpected surprises. In the process of fighting against Mu Chun Shen, she gradually discovered Mu Chun Shen's kindness and sense of responsibility, and gradually fell in love with Mu Chun Shen. At the same time, she realized that there was a background/history behind this assassination mission.