In December 1969, the gripping tale unfolds with South Korean fighter pilot Tae-in intercepting an airliner that has fallen into the hands of a North Korean hijacker. Struggling with a moral dilemma, Tae-in makes the courageous decision to refrain from firing on the plane before it crosses into North Korean airspace. This decision is particularly harrowing for him, as he recognizes the plane's pilot to be his dear friend and former mentor, Young-sook. Ultimately, the aircraft reaches its destination in North Korea, leading to severe repercussions for Tae-in, who is expelled from the air force for defying orders. While 39 of the 46 passengers manage to return to South Korea, seven remain trapped, along with the four crew members, including Young-sook, trapped in North Korea indefinitely. In the aftermath, Tae-in seeks solace in his profession as a pilot for Korean Air.
Fast forward to January 1971, where the stakes rise as Tae-in and his colleague Gyu-Sik prepare for a critical Fokker F27 flight from Sokcho Airport heading to Gimpo International Airport in Seoul. Shortly after takeoff, chaos erupts when passenger Yong-dae triggers two improvised explosive devices. One explosion causes a significant breach in the cabin floor, injuring several passengers and a sky marshal, while the second blast wreaks havoc on the cockpit door, momentarily blinding Gyu-Sik and thrusting Tae-in into an unexpected leadership role. Yong-dae menaces the pilots with a knife and another bomb, demanding that they redirect the plane toward North Korea.
Amidst intense turbulence, a group of brave passengers attempts to wrest control from Yong-dae, but he seizes the opportunity to obtain the air marshal's firearm. Desperation ensues as Tae-in attempts to land at a secluded airstrip, but Yong-dae's threats intensify, culminating in him shooting Tae-in in the leg. In a candid moment, Yong-dae reveals the heavy burden he bears: being shunned due to having a North Korean brother, fueling his belief that he would find sanctuary in North Korea.
As the drama unfolds, South Korean fighter jets, piloted by Tae-in's former comrade Dong-cheol, scramble to intercept the hijacked plane, alerting Tae-in of incoming North Korean fighter jets as well. In a tense aerial dogfight, Tae-in deftly navigates through enemy fire, while Yong-dae loses his grip on the gun amid the chaos. With time running out and options dwindling, Tae-in and Gyu-Sik resolve to make a crash landing on a beach. In a heart-stopping confrontation, Yong-dae tries to reclaim control of the aircraft but ultimately meets his end at the hands of the sky marshal.
In the aftermath of the struggle, as Yong-dae's final explosive device ignites, Tae-in makes a selfless choice, using his own body to shield the passengers from the imminent blast, which gravely injures him. Gyu-Sik manages to bring the plane down on the beach with the assistance of a flight attendant and a severely wounded Tae-in, allowing all passengers to safely evacuate. However, Tae-in succumbs to his injuries, leaving behind a poignant legacy of bravery and sacrifice while still seated in the cockpit.
