Detective Oh Byung-ho, Ha Myeong-jung, is assigned to investigate the murder of a local brewer in Munchang. The case quickly reveals a tangled past connected to the Korean War, where Yang Dal-soo, Lee Dae-geun, once helped capture four guerrillas and killed nine. One of the surrendered guerrillas, Kang Man-ho, Bob Hyeon Gil-su, recalls that he was trusted by Son, his eccentric commander at Jirisan, with the safety of his daughter Son Ji-hye and with a map pointing toward a fortune tied to a landlord family. The commander was removed from his post and executed for refusing an order from Pyongyang to launch an all-out attack from the mountains; in the ensuing assault, thirteen people died, including ten guerrillas such as Man-ho, as well as Ji-hye, Hwang Ba-woo, and Han Dong-ju.
In the aftermath, the story threads back to a tense moment when the guerrillas, hiding in the basement of a school, tried to shield Ji-hye from danger and plotted to surrender to the enemy with Yang’s help. Hiding out under pressure, the group faced a militia surrounding the school, and a fire broke out, trapping those who attempted to escape. Ji-hye and Bau survived the chaos, while Man-ho served a two-year sentence and withdrew from public life. The investigation grows colder as Byung-ho confronts the possibility that Man-ho could be the father of Ji-hye’s child, a revelation that would explain a motive steeped in guilt and protection, a line of thought that pushes him toward a stubborn, relentless pursuit of the truth.
Despite mounting frustration, Byung-ho presses on and is urged by his superior to keep digging. He travels to Seoul to locate Ji-hye, who has become entangled in a web of memories and secrets. Ji-hye recalls giving birth to a son named Taeyoung and living a relatively stable life with Bau. Their search for a fortune on the map leads them to rely on Yang to access Jirisan, and the pursuit deepens as they uncover connections between the fortune and the people who once held power. They locate the fortune, but Bau is arrested for the murder of Han Dong-ju, a consequence of Bau’s earlier act during the surrender. Ji-hye seeks more help from Yang, who guides her toward the bedroom of Bau’s prosecutor, setting off a chain of events that ends with Bau’s prison sentence and Ji-hye living with Yang for a time, bearing a daughter and leaving Taeyoung in Bau’s care.
As the investigation unfolds, Byung-ho learns that Kim Jungyeop, who was murdered before Yang’s time, was Bau’s prosecutor, prompting him to track Bau’s family and the life Bau tries to rebuild after parole. Taeyoung grows distant from Bau, and then vanishes, prompting Bau to travel to Seoul in a desperate bid to find him. Convinced that Taeyoung might be the killer, Byung-ho discovers that Ji-hye and Bau have reunited and have placed Taeyoung in a mental hospital to protect him from prosecution. Behind the scenes, Eom, a friend of Byung-ho, leaks a conflicting narrative—Dong-ju is alive and Bau is innocent—an assertion reinforced when Yongjae is found in Dong-ju’s burial mound. Taeyoung is abducted from the mental hospital, and Eom, along with Byung-ho, tails an associate of Dong-ju to mount a rescue and arrest Dong-ju, who had been living off hush money from Yang and Kim and who masterminded a string of deaths through Taeyoung.
Yet the plot twists intensify when Bau chooses to leave home to attempt suicide in a bid to prove Taeyoung’s innocence. Byung-ho delays his own detainment for the killing of Bong-ju, but the effort cannot avert tragedy. At Bau’s funeral, Ji-hye takes her own life while mourners drift into sleep. Byung-ho scatters the ashes of both Bau and Ji-hye in the river, standing in front of witnesses and police who watch him, and then walks out to the riverbank to meet his own end, completing a harrowing cycle of loss, guilt, and unresolved justice.
