An intricate plot unfolds as sophisticated components are smuggled into the United States disguised as a fish shipment, involving espionage at a prominent hotel suite and the theft of a crucial wallet labeled "JR." This wallet contains a photo of a daughter along with various credit cards and identification documents.
Lisa, who is employed at the luxurious Lux Atlantic Hotel in Miami, is currently on leave but frequently receives calls from her colleague, Cynthia. As they discuss critical guests and customer complaints, Cynthia informs Lisa that Deputy Secretary of Homeland Security, Charles Keefe, will be arriving the next morning. Keefe has gained notoriety for his stringent stance on domestic terrorism, attributing it to the influx of illegal immigrants in Southern states.
Following her grandmother's funeral, Lisa Reisert (played by Rachel McAdams) arrives at Dallas Love Field, preparing for a red-eye flight back to Miami. She has family ties there, as her father, Joe Reisert, resides in Miami while her mother moved to Texas after their separation three years ago. During her wait at the airport, she encounters the charming Jackson Rippner (portrayed by Cillian Murphy), and they share a drink, enjoying their conversation.
On the plane, various passengers include a girl named Rebecca, an elderly lady, a blonde woman, and two young boys. Lisa bonds with the elderly lady over a self-help book by a favorite author. Much to her shock, Jackson is seated next to her, in 18F, while she occupies 18G.
After the flight takes off, Jackson's friendly facade collapses into something menacing. He reveals he’s linked to a domestic terrorist organization with a plan to assassinate Charles Keefe. Lisa's role at the hotel is a critical component in their scheme. Jackson demands that Lisa make a call to change the Keefe family's suite from 3825 to 4080, where a missile launched from a harbor boat is intended to strike. He holds her father, Joe (played by Brian Cox), hostage, threatening that if she disobeys, her father will be killed, even showing her Joe's stolen wallet as evidence.
In a tense ordeal, Lisa tries to delay the call, insisting she must know her father's welfare first. Jackson hesitates but allows the call for a brief moment before cutting it short partway through. When he steps away to assist another passenger, Lisa seizes the opportunity to scribble a note in her book before Jackson returns, only to be caught, resulting in a violent headbutt.
Amidst turbulence on the flight, Lisa attempts to contact Cynthia, but her efforts are thwarted when Jackson becomes suspicious. In a desperate move, she tries to leave a hidden message on the bathroom mirror warning of an impending bomb threat, but Jackson quickly wipes it out, reminding her of the risks involved.
Eventually, Lisa complies with Jackson’s orders and informs Cynthia to relocate the Keefe family. As the plane lands in Miami, Lisa reveals a past traumatic experience, staying resolute to fight against Jackson. In an explosive confrontation, she stabs him with a pen and makes a daring escape just before the plane arrives at the gate.
Once outside, Lisa commandeers an SUV, urgently notifying Cynthia to evacuate the hotel suite. Thanks to her timely warning, the Keefes, Cynthia, and U.S. Secret Service agents manage to flee moments before a missile obliterates their planned suite. In the chaos, Lisa narrowly escapes a hit-man while tragically taking his life in self-defense before reuniting with her father, who has called 9-1-1.
In a climactic confrontation at home, Jackson pursues Lisa. After a fierce struggle, he gains the upper hand until Joe, recovering, ultimately saves Lisa by shooting Jackson. Lisa then returns to the hotel where Keefe expresses his heartfelt gratitude to both her and Cynthia for their courage and decisive actions that saved his life and the lives of others.
