‘Emergency Declaration’: If an aircraft faces a potential disaster, and normal flight can no longer be maintained, the pilot calls for an unconditional landing. Veteran chief police detective In-ho receives a tip about a man threatening a terrorist attack against a plane. While investigating, he discovers that the suspect has actually boarded flight no. KI501. Despite his phobia of flying, Jae-hyuk decides to go to Hawaii for the sake of his daughter’s health. At the airport, he is distracted by a strange man who hangs around, speaking to them in a menacing way. Flight no. KI501 departs Incheon Airport for Hawaii, but soon afterwards a man dies for mysterious reasons. Fear and chaos spread quickly, not only inside the plane, but also on land. Hearing this news, Transport Minister Sook-hee sets up a counterterrorism task force and calls an emergency meeting in order to find a way to land the airplane.