Joint Security Area

Two North Korean soldiers are killed during a tense confrontation at the Joint Security Area near the Bridge of No Return, while a wounded South Korean sergeant, Soo-hyeok, tries to flee back to the South. Southern troops intervene as gunfire erupts, and Soo-hyeok is rescued despite his injuries. The incident triggers an urgent cross-border crisis and a request for accountability.

Two days after the incident, Major Sophie E. Jean of the Neutral Nations Supervisory Commission leads a formal inquiry into the conflicting accounts. The investigators seek to uncover what happened and why both Koreas offer different versions. The border-house interrogation rooms become the center stage for testimony and scrutiny.

Soo-hyeok confesses that he shot three North Korean soldiers after waking bound in the border house. He claims he had been knocked out while relieving himself and later freed himself, leading to the shootings. The confession begins to shape a narrative that places him at the center of the violence.

North Korean sergeant Oh Kyeong-pil presents a counter-narrative, claiming Soo-hyeok barged into the border house and started shooting before anyone could react. The conflicting stories intensify the tension, as Sophie weighs competing testimony. The investigation deepens as the truth remains elusive.

Woo-jin’s autopsy shows eight gunshot wounds, suggesting a long-held grudge, and a missing bullet that cannot be accounted for. The forensic detail complicates the timeline and hints at hidden loyalties among the soldiers. The findings deepen the mystery surrounding who shot whom first.

Nam Sung-shik attempts to commit suicide by leaping from the interrogation-room window, a moment of raw vulnerability under the weight of the case. The moment exposes the emotional strain on witnesses under formal scrutiny. Authorities stabilize him and press forward with the interview.

Sophie perceives an unusual, almost familial tension between Kyeong-pil and Soo-hyeok during a tense meeting. The glances and quiet exchanges hint at a mutual friendship with Woo-jin that could complicate a neutral verdict. Her suspicions drive her to probe deeper into the personal relationships among the soldiers.

In flashbacks, Soo-hyeok becomes lost on the North Korean side and nearly triggers a mine. Kyeong-pil and Woo-jin find him, deactivate the mine, and form a bond with the South soldier. They begin exchanging messages by dropping notes over the Bridge of No Return to stay connected over the following weeks.

The four soldiers—Soo-hyeok, Kyeong-pil, Woo-jin, and Sung-shik—become friends and vow to keep politics out of their personal bond. They choose loyalty to their respective countries, forging a fragile camaraderie that complicates the moral landscape of the case. The border becomes a place of trust, not just conflict.

Tension peaks as Soo-hyeok and Sung-shik return to the North guard house to bid goodbye and celebrate Woo-jin's birthday. A North officer discovers them, triggering a dangerous standoff among the soldiers. The emotional stakes rise as loyalties are tested on the edge of war.

During the standoff, Sung-shik panics and shoots the commanding officer who reaches for his radio. Woo-jin panics and betrays his friends by reacting as well, and Sung-shik then shoots Woo-jin. In a daze, Sung-shik also fires multiple rounds into Woo-jin's corpse, heightening the chaos and muddying the truth.

Kyeong-pil persuades Soo-hyeok and Sung-shik to flee with a false alibi of being kidnapped, then discards evidence that he and Woo-jin were fraternizing with the South. Soo-hyeok shoots Kyeong-pil in the shoulder to complete the alibi and facilitate their border escape. Soo-hyeok and Sung-shik slip across the border while he is left behind wounded.

Back in the present timeline, Sophie is removed from the case after it is revealed her father had North Korean ties. She privately attempts to learn the truth from Kyeong-pil and then Soo-hyeok. Before leaving, she gives Soo-hyeok the lighter that started their acquaintance, hinting at the deeper bonds among the soldiers.

On his way out, Soo-hyeok steals an officer's pistol and commits suicide out of guilt for Woo-jin's death and Sung-shik's suicide attempt. The case ends in tragedy, and a final image—an American tourist's photograph—captures all four soldiers together in the Joint Security Area before the incident.