Chul-soo is the only son in the most notorious criminal family in Korea, and he also has innate nature of crime that comes from his parents. As fate would have it, Chul-soo falls in love with Young-hee, a detective and a daughter of a cop. To persuade Young-hee’s father who is completely against their marriage, Chul-soo promises that he would pass the cop exam and studies for 7 full years. Chul-soo studies with all his might and is close to passing the exam, but his parents try desperately to sabotage his wedding and his future as a cop.
Meanwhile, Young-heeand her family are ordered to investigate a serial murder case, and while still studying for his cop exam, Chul-soo helps them out with the case by borrowing his parents’ expertise.