Two souls board a train to the afterlife after very different deaths. Kim Ja-hong is an ordinary office worker who dies from liver disease after years of exhausting company dinners and drinking. Sergeant Yoo Seong-yeon is accidentally shot during military service and secretly buried alive by officers trying to conceal the incident.

At Chogun Gate, Ja-hong meets Jin Gi-han, a brilliant public defender who has rejected a prestigious career to represent ordinary souls. Gi-han explains that the dead must face seven trials over 49 days before being assigned to one of the gates of reincarnation.

Ja-hong is judged for childhood theft, failing to express love for his parents, excessive drinking, minor acts of cruelty, and exploiting subcontractors at work. Gi-han shows that Ja-hong returned a stolen wallet, remembered his parents’ birthdays, and was often a powerless employee trapped within an unjust corporate system. A small act of kindness toward an elderly woman also returns to save him during his journey. After passing all seven trials, Ja-hong enters the light and begins the next stage of existence.

Seong-yeon, meanwhile, escapes from the train because of his rage over his death. He kidnaps the grim reaper Deok-chun, who learns how he was buried while still alive and persuades Gang-rim to investigate. Seong-yeon’s resentment transforms him into a dangerous spirit, but he later forgives the private whose accidental shot caused his death.

Gang-rim destroys the vengeful spirit without destroying Seong-yeon’s soul. He and Deok-chun allow Seong-yeon to enter his mother’s dream and say goodbye, while the officer responsible for burying him is marked for punishment after death.

Seong-yeon finally returns to Chogun Gate, where the other souls have already been assigned lawyers. Gi-han arrives, introduces himself as Seong-yeon’s defender, and prepares to guide him through the seven trials.