The film opens at an airport, where Alex Martin is eager to catch a flight to Denver for her wedding. Unfortunately, she learns that her flight has been canceled due to an impending storm. Simultaneously, Ben Bass is trying to board a plane for an urgent heart surgery he needs to perform on a 10-year-old boy, but his flight is also grounded. In a twist of fate, Alex approaches Ben and proposes a solution to their mutual travel dilemma.
The two soon meet Walter, the owner of a charter plane that can take them to their destination. Walter brings along his dog, who seems to be none too friendly towards Ben at first. During the flight, Alex reveals her profession as a photographer, mentioning an assignment where she photographed neo-Nazis. As the journey progresses, ominous storm clouds gather above them. While Walter attempts to communicate via radio, he suddenly suffers a stroke. Ben rushes to assist, but Walter loses motor functions, resulting in a tragic crash into the mountain.
When Ben regains consciousness at night, he discovers Walter dead and Alex unconscious with a severe leg injury. Ben tends to her wounds before passing out from exhaustion. The following morning, Ben emerges from the wreckage, retrieves Walter's body, and gives him a proper burial in the snowy mountains.
Alex wakes up the next day to Ben's grim account of their situation. They quickly realize their limited food supply poses a significant threat to their survival, and they begin searching for ways to signal for help. To keep their spirits up, they engage in conversation about each other's lives. Ben spots a plane overhead and tries to signal it with a flare, but it is unsuccessful. While he goes in search of supplies, Alex listens to a recording from his wife, which reveals a painful part of his past. Meanwhile, danger lurks as a cougar stalks Alex and the dog outside. The dog bravely confronts the cougar but gets bitten. In a show of courage, Alex uses a flare to scare it away. Ben treats the dog’s injury and prepares the cougar they killed for dinner.
Days pass as tension builds. Alex suggests they move forward, while Ben insists they stay put. Eventually, they decide to leave the wreck and pursue a glimmer of hope that Alex spots through her camera. However, they are met with a raging river that blocks their path. They seek shelter in a cave for the night, both grappling with the reality that they could die in the unforgiving wilderness.
The next day, in a moment of vulnerability, Ben asks Alex to take a picture of him, fearing it may be his last. Alex recalls a haunting memory of taking a photo of a girl just before she died, leading her to refuse Ben's request. As they trek on, they become separated from the dog, and Ben finds a cabin. While checking it out, Alex falls through thin ice, plunging into freezing water. Ben rushes to save her, risking his own safety. After rescuing her, he builds a fire to revive her.
Alex remains in a comatose state for days, yet when she finally awakens, tensions rise when she explores Ben's past through his recorded message from his wife. After an emotional conversation, they share a kiss, leading to an intimate moment that deepens their connection. Ben reveals more about his late wife, Sarah, whose struggle with a brain tumor drove them apart.
One day, he spots a lumber mill in the distance. As he heads back to the cabin, he inadvertently steps into a bear trap, leaving Alex to seek help on her own. Exhausted and near collapse, she manages to attract a truck driver before losing consciousness.
Ben wakes up in a hospital, where he finds Alex with her fiancé, Mark. Though Mark is grateful to Ben for saving Alex, their reunion is bittersweet, filled with unspoken feelings as Ben quietly leaves the room.
As time passes, they continue to adjust to life without each other. Ben returns to South London and adopts the dog, while Alex attempts to move on with her life alongside Mark. Despite her new relationship, memories of Ben linger, especially during a party where friends suggest she share her photos from their harrowing experience. However, she hesitates, knowing that one picture holds profound meaning.
Finally, Alex sends Ben some of the photos along with a note that he alone can interpret. This gesture prompts Ben to reach out to her. Eventually, they meet in Manhattan at a restaurant. Ben confesses his silence stemmed from assuming Alex had moved on. To his relief, she reveals that she couldn't go through with her engagement and has realized she loves him. Yet, when it comes time to profess their feelings, Ben holds back. They part ways, only to quickly regret their decision. In a surge of emotion, they turn around and rush back into each other's arms, cementing the bond forged under unimaginable circumstances.
