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.

Seong-ah, the main character who lives in a camp at a welfare facility in the cathedral, is given a confession and is given a continuous service (a practical task for atonement given by the bride after confessing). She tries her best to perform penance, but it doesn't work out as she wishes. What is wrong with her?