The love story of a single dad, Kang Poong Ho, who raises his 7 year old son alone after being abandoned by his first love, Yoon So Yi. By day he works as a pest exterminator and by night he is a martial artist. Jeon Ha Ri, is a medical student from a wealthy family who falls for Poong Ho. She secretly teaches Poong Ho's son, San, how to play the piano. Poong Ho's first love is also his son's mother who is a cold and proud woman who left her family to study abroad as a pianist. She was sponsored by Jeon Ki Suk who happens to be her fiancée and Ha Ri's father.
The drama is about the assassination attempts on Emperor Jeong Jo's life during the 8 day period when he left the palace for a ceremony to honor his father who was killed by his grandfather.