While investigating a terroristic threat that goes viral online, Korean authorities discover that a suspect has recently boarded an international flight bound for the United States. When a healthy passenger on the same flight suddenly dies a gruesome death of unknown cause, panic erupts both in-flight and on the ground. With steadily decreasing fuel and international refusals to offer aid, the captain and crew will be forced to take unprecedented emergency measures in an attempt to save the lives of their passengers.

Sang-hyeon (Song Kang-ho) is the owner of a launderette and a volunteer at the nearby church, where his friend Dong-soo (Gang Dong-won) works. The two run an illegal business together: Sang-hyeon occasionally steals babies from the church's baby box with the help of Dong-soo, who deletes the church's CCTV footage that shows a baby was left there, and they sell them on the adoption black market. But when a young mother, So-young (Lee Ji-eun), comes back after having abandoned her baby, she discovers them and decides to go with them on a road-trip to interview the baby's potential infertile parents. Meanwhile, two detectives, Soo-jin (Bae Doona) and Detective Lee (Lee Joo-young), are on their trail.