Based on real-life cases, this Korean drama focuses on a group of detectives in the Seoul Gangnam Police Homicide Division. At the forefront of the team, it is the hotheaded detective Park Se Hyuk and the cold, commanding police chief, Jung Il Do. Se Hyuk's impulsive, act-first-think-later methods, instincts honed on the streets, and pesky habit of threatening resignation clashes with his superior Il Do's strict, by-the-book style. The two also share a painful past, with Il Do being the detective on the case involving the death of Se Hyuk's daughter. Along with tenacious reporter Jo Min Joo and the rest of the homicide squad, they must now overcome their differences to solve crimes together.