This is a drama about a detective who beats up criminals with all hisheart and a hacker-turned-criminal student who solves everything with his smart head, meeting as a professor and student at a police university and co-investigating a case.

Yoo Dong Man (Cha Tae Hyun)is a former detective. He worked as a detective for 20 years in variousdepartments, including violent crimes and cyber crime. He would often act impulsively. Yoo Dong Man now works as a professor at the police university. His rookie students include Kang Sun Ho (Jin Young) and Oh Kang Hee (Krystal). Kang Sun Ho was a hacker and he is smart. Oh Kang Hee is righteous and honest.