A commercial airliner departs from South Korea, bound for Hawaii, with passengers completely unaware of the terror that awaits them. Among the passengers are Jae-hyuk, a father traveling with his sick daughter in hopes of finding her treatment abroad, and Jin-seok, a man exhibiting suspicious and erratic behavior. On the ground, upon learning of a potential threat aboard the flight, In-ho, a hard-nosed police detective, races against time to uncover a horrifying plot that could imperil everyone on the plane. Tensions escalate as this threat is revealed to be a deadly virus released mid-flight, spreading rapidly among passengers and crew, causing chaos and panic.

Simultaneously on the ground, government officials struggle to respond to a crisis that threatens to spiral out of control. Faced with reluctant neighboring countries unwilling to aid or allow them to land, the situation becomes dire as communication falters between air and ground. As fear mounts and passengers begin succumbing to the illness, resourceful crew members and determined civilians on the flight must confront escalating stakes with dwindling options for survival. Meanwhile, In-ho races to track down clues that could lead to the mysterious perpetrator behind the attack. Amidst personal sacrifices and moral dilemmas that challenge both those in flight and on land, hope hangs by a thread as they strive to contain what feels like an impossible disaster.