A North Korean female secret agent works alongside her partner, Chul-seung, as they clandestinely infiltrate a government building to obtain sensitive North Korean documents. After successfully stealing the classified files, the alarming twist occurs—she shoots Chul-seung in an act of betrayal and escapes.
Fast forward ten years later to a bustling neighborhood in Seoul, where we meet Mi-young, portrayed by Uhm Jung-hwa. Mi-young earns a modest living selling delicious twisted bread sticks, while her husband, Suk-hwan, is busy repairing computers. The family, which includes their young daughter Na-ri, finds joy in simple pleasures. One day, they receive exciting news: they have won a free vacation to Hawaii. Initially, Mi-young hesitates to accept, fearing the high costs of travel. However, upon seeing her daughter return home in tears, lamenting that she has never traveled like her friends, Mi-young's heart softens, and she chooses to go on the trip.
As the departure day arrives, a covert team of North Korean agents is dispatched with a singular focus: to locate the secret agent, who is believed to be on board the flight to Hawaii. Leading this operation is Chul-seung, whose miraculous survival after being shot years before is nothing short of astonishing. They are not alone on this flight; the presence of a National Intelligence Service (NIS) agent assigned to monitor events onboard adds to the tension, along with a mysterious young woman whose face is concealed by a mask.
While Mi-young and Na-ri enjoy the luxuries of first class, Suk-hwan finds himself seated in economy class, engaging in a friendly conversation with an elderly passenger. As the plane flies overhead, chaos erupts when the North Korean agents draw their weapons and commandeer the aircraft. Luckily, Mi-young is in the rear lavatory, evading immediate detection. Meanwhile, the NIS agent remains completely oblivious, sleeping soundly through the unfolding hijacking.
Looking for the secret agent, the North Korean operatives initially suspect the masked woman on board, only to discover she is none other than famous actress Ahn Se-ra, traveling incognito. When one of the agents attempts to assault Mi-young, she showcases her unexpected martial arts prowess, swiftly incapacitating him. It is then unveiled that Mi-young is indeed the sought-after secret agent, having undergone plastic surgery to alter her identity before escaping to South Korea, where she built a new life, marrying Suk-hwan and raising their daughter.
In a surprising twist, Suk-hwan covertly accesses the cargo hold and uses a computer to alert the NIS to the hijacking, revealing his own hidden past as a former secret agent. Disguised as a flight attendant, Mi-young bravely confronts and takes down several hijackers, but soon she and her husband find themselves captured. To shield herself, Na-ri cleverly claims that Ahn Se-ra is her mother. Confusion ensues when the hijackers turn on Chul-seung, revealing their true intention to crash the plane into the ocean while transporting Mi-young back to North Korea for a hefty payout.
Imprisoned alongside Mi-young and Suk-hwan, Chul-seung explains the dire situation; Mi-young's father once developed nuclear weapons that can only be activated by scanning her retina. If these weapons were to come into the wrong hands, global repercussions would be catastrophic. With a daring twist of fate, a compassionate flight attendant intervenes, freeing Chul-seung and the couple, enabling them to combat the North Korean agents as a united front.
Just when hope seems to blossom, the elderly airport passenger takes Na-ri hostage, intensifying the stakes. He reveals a haunting truth: he was responsible for the murder of Mi-young's father. With intentions to force Mi-young back to North Korea, he shows the depth of his malice, but in a fierce bid for freedom, she decisively kicks him out of the aircraft. The teddy bear, which was given to Na-ri by the old man, is revealed to conceal a time bomb intended to obliterate the plane. In a heart-stopping moment, Mi-young manages to throw it out moments before it detonates.
As fate would have it, Chul-seung bids farewell to Mi-young and her family, parachuting away from the chaos. Eventually, the flight concludes without further incident, and Mi-young's family is left to relish in the prospect of a splendid vacation in Hawaii. As a final twist, the NIS agent finally rouses from his slumber on the now-empty plane, only to discover a series of messages from his superiors announcing his termination from the agency.
