New recruit By Detective Lee no longer feels the need to bestow mercy on the corruptive activities of By Detective Kang. He believes By Detective Kang must be removed from the force for good. Therefore, By Detective Lee constantly suggests to By Detective Kang to resign. In response, the anxious By Detective Kang attempts a final counterattack by handing him unsolved cases and ordering him to solve them. But instead, By Detective Lee solves many of them all at once. At this time, a big theft occurs. During the investigating process, unable to forget old habits, By Detective Kang makes the mistake of slipping a diamond for himself. By Detective Kang thinks he got away with his little deceit but it is soon detected by By Detective Lee. With this incident, By Detective LEE makes a deal with By Detective Kang – he will forgive him only if he solves another pending case. However, the case that By Detective Lee hands him seems impossible to solve.