A mystery arson investigation drama that follows a fire investigator uncovering the truth behind a string of serial arsons—where the prime suspect is his deceased younger brother.
In the city of Pyean, with a population of 140,000, a series of fires breaks out at public facilities. Fire investigator Seo Do-kyung suspects arson, but faces mounting pressure from the police that prevents him from pursuing the theory.
The situation escalates when a massive fire engulfs a public bus depot, and the prime suspect turns out to be Cha Jung-hyuk—a skilled firefighter and the older brother of a former student arsonist, Cha Min-do. With Do-kyung's help, Jung-hyuk is proven innocent, but in the process, the possibility of Min-do's own innocence begins to emerge.
A special task force is formed to investigate the serial arsons, and Jung-hyuk returns to the front lines as the team leader. As he delves deeper into the case, he encounters Kim Young-hoo, a man eerily resembling his dead younger brother—throwing him into emotional turmoil as truth, guilt, and memory collide at the heart of the flames.