A master thief appeared in South Korea with a strange whereabouts. Every time, he found and ransacked the carefully hidden property of the rich man Li Zhengmin . Li Zhengmin is a chaebol who knows everything in black and white, and he vowed in despair to capture this mysterious master alive.
A prosecutor (played by Cheng Dong Il) who was struggling but upright found Li Zhengmin, After discovering his crime of monopolizing the market through violence and bribing officials, Li Zhengmin threatened the prosecutor by wooing him to help him investigate the mysterious person who stole a huge sum of money. Through investigation, Li Zhengmin found that the mysterious person may be the prosecutor's brother-in-law Hong Wuhe (played by Li Bunxiu), but Hong Wuhe is just a gentle and elegant piano teacher.
It turns out that the Hong Moo-hyuk family is the eighteenth generation descendant of Hong Gil-dong, an ancient thief. He is a great hero in the hearts of the poor. His last wish is to use all stolen things for the poor. Therefore, Hong Wuhe's family has different roles during the day, but they will become thieves at night.