Yoo Seol-Ok liked mystery novels and wanted to become a detective, but she gave up her dream after marrying. Now, she is a housewife with a husband who works as a prosecutor. She meets Ha Wan-Seung. He is a passionate detective and they decide to collaborate to solve cases.

Kim Gwan-Chul used to work as an accountant, but now he works as a chief for a company. He is man who follows his principles and uses common sense. He also stands up for those in weaker positions.