20 years ago Moo-Yeom’s father was a suspect in the "Gap Dong” serial murder case. Because of the detectives’ oppressive investigation, Moo-Yeom’s father killed himself. Now, Moo-Yeom is a detective and works to capture the killer Gap Dong. The statue of limitations has expired for the serial murder case and Moo-Yeom resigns to the belief that Gap Dong is dead. New clues though for Gap Dong appears in front of Moo-Yeom and he sets out to catch him once and for all.

Of the high-rolling top 'hot celebrities' of the wealthy upper class in Korea's high society, Kang Hye Na is the one desired by the men, feared and hated by the women. Being the only successor to the largest conglomerate company, Kang San Group, Kang Hye Na has both the looks and the background. She is the owner of the 'Lady Castle' and lives a 'princess-like' life with her servants.

A wealthy young man and a poor stunt woman fall for each other, but when their souls swap they soon learn how different their two worlds are.

Ok Da-Jung is the youngest team leader in the cosmetics industry. She has divorced three times so far. She doesn't care what others think about her and she also has quite a temper. Nam Jung-Gi works as a section chief at the same cosmetics company as Ok Da-Jung. Unlike her, Nam Jung-Gi has a timid and nice personality. He can't say anything that makes others uncomfortable. He is able to make Ok Da-Jung's blood boil.

At a difficult place in his marriage and career, a middle-aged man gets a shot at a do-over when he's transformed back into his 18-year-old body.