In this emotionally grounded drama, Park Shin-hye plays Ye-seung, a determined law student who chooses her late father’s wrongful conviction as the focal point of her mock trial, a choice that threads through two timelines and tests hope, memory, and justice. Ye-seung’s path is inseparable from her father Yong-gu, Ryu Seung-ryong, a man with a developmental disability whose life spirals into tragedy after a heartbreaking chain of events that leads to a conviction he did not deserve.
The narrative flashes back to 1997, when six-year-old Ye-seung and Yong-gu glimpse a Sailor Moon backpack through a storefront window. Yong-gu surges to buy it, only to be blocked by the police commissioner and his daughter, an event packed with confusion and tension. When the girl tied to the family’s mask of misfortune slips on an icy market floor and a brick falls, the girl dies. Yong-gu is arrested for rape and murder as bystanders misinterpret his desperate attempts to help, and he is sent to prison, separated from Ye-seung.
In prison, Yong-gu shares a cramped cell in a place known as Room 7 with five inmates who initially doubt him because of the crime he’s accused of and his disability. Yet a pivotal moment comes when Yong-gu saves the life of his cellmate and gang leader, So Yang-ho, from a deadly rival attack. Touched by the act, Yang-ho promises to repay the favor in any way he can. The bonds between Yong-gu and these inmates deepen, and Ye-seung’s world gradually crawls toward the possibility that her father might be innocent.
The story follows the inmates’ orchestration of Ye-seung’s access to the prison. When Ye-seung visits during a choir performance, she meets Yong-gu’s circle of companions, who come to see him as more than the report of a crime. The warden eventually recognizes Yong-gu’s innocence as Yong-gu’s bravery—especially when he saves the warden from an arson attempt—begins to shift perceptions. The warden allows Ye-seung to visit Yong-gu after school on a regular basis, and the family’s longing becomes a thread that holds the film together.
Before the trial, the Room 7 inmates train Yong-gu to answer tough questions from prosecutors. He grows adept at responding to interrogations, learning to navigate the pressures of a courtroom with a grace that surprises everyone. However, a violent blow from the commissioner shatters the sense of safety Yong-gu had earned, and in a desperate act to protect Ye-seung, Yong-gu chooses to lie—claiming he killed the commissioner’s daughter to shield his daughter from danger. This lie leads to a death sentence, and the date of execution looms on December 23, a birthday that Ye-seung herself shares with the memory of her father.
In a bid for escape and hope, the inmates secretly construct a plan around a hot air balloon. During a prison concert, they stage a ruse to smother the guards’ suspicions while Yong-gu and Ye-seung are carried away by the balloon. The escape ride narrowly succeeds, but the rope catches on barbed wire, thwarting their full passage to freedom. On the day Yong-gu’s execution is scheduled, the inmates mark Ye-seung’s birthday with a quiet, bittersweet farewell before the process goes forward.
Sixteen years pass, and in the present, Ye-seung, the warden, and the Room 7 inmates gather for a mock trial that reexamines Yong-gu’s case. A judge overturns the original verdict, granting a posthumous acquittal and issuing a court order to reopen the case, even if it holds no legal weight in the immediate sense. The ceremony brings a measure of closure to Ye-seung, the room’s surviving members, and the warden who stood by Yong-gu. The film circles back to Ye-seung’s memory of the hot air balloon, a final image of her father and younger self waving goodbye as the balloon drifts away, leaving a sense that truth and love can outlive the worst misjudgments.
