Choi Kang-woo is a former police and leader of Taeyang Insurance's investigators team, decides to create his own investigation team, after an airplane crash that took the life of his wife and son. He then meets Kim Min-joon, a genius former swindler whose brother was also a victim of the crash, thus begin their rivalry and cooperation. The drama portrays the reality of Korea through diverse insurance crimes that are prevalent in the country. There are the 'copy cats' that imitate and improve the existing crimes, and the 'mad dogs' who catch these bad cats.