A pilot named Jake Barnes flies a cargo plane high above the frozen expanse of the Alaskan wilderness, delivering toilet paper for Quincy Air Service. Below, a polar bear cub Cubby and its mother play in the snow, blissfully unaware that two ruthless poachers, Perry and the relentless Koontz, are watching from the shadows. The mother bear is killed, and the cub is trapped in a cage, destined to be sold alive to a client in Hong Kong for a fortune, even as Koontz argues that they should kill it instead.
In the meantime, the young members of Jake’s world—Jessie Barnes and her friend Chip—observe wildlife from their kayaks before heading home. Jake lands the plane and reunites with his son, Sean Barnes, who is quietly taking out his anger about their family’s move to Alaska following his mother’s death. Jake tries to reassure him, but Sean’s frustration lingers as the family struggles to adjust to a new life.
An emergency assignment sends Jake on a critical run to Douglas, but disaster strikes when the engines stall and the plane crashes in a remote area near Devils Thumb. The crash leaves Jake missing and presumed in trouble, and Sean and Jessie decide to take matters into their own hands, determined to find their father despite the chilling odds.
The siblings embark on a rugged trek through glacial seas and treacherous terrain, paddling through the Gulf of Alaska and scrambling ashore near the poachers’ camp. They stumble upon the cub locked in a cage and the cub’s mother missing, and in a moment of mercy they set the cub free. Perry and Koontz quickly learn that their captive has escaped, renewing the hunt as they attempt to recover their prize and outpace the determined kids.
Day two of the search sees Jessie and Sean continuing on foot, with the polar cub following close behind. Perry and Koontz close in on the kids’ trail, desperate to reclaim what they’ve lost. In a bid to mislead a search helitack pilot, the poachers ambush the situation, hiding the kids’ kayak and leaving a fake clue—a piece of an oar—to send the helicopter off on a wild goose chase. Charlie arrives by helicopter to locate the kids, but the criminals manipulate the moment to their advantage.
The group presses on, taking shelter inside an old rusty cabin before switching to a canoe to pursue the trail down a winding river. A waterfall upends their voyage, and they are rescued by Chip and his grandfather, Ben, who are out on a caribou hunt. Chip’s father urges Jessie and Sean to go home, but Ben and Chip insist on helping the two continue their mission. With Cubby in tow, the trio presses onward, the cub now nicknamed simply Cubby by the kids.
Back on the poachers’ tail, Charlie tracks Perry and Koontz to the high ground around Devils Thumb and reports their camp. He heads back toward the rescue zone, while the kids and their new allies press toward the crash site, driven by the hope of reuniting the family.
Cubby eventually leads Jessie and Sean toward Devils Thumb, but Perry and Koontz ambush them from the skies with a helicopter and tranquilize Cubby enough to snatch him away. Koontz’s half-measures backfire when Cubby awakens and fights back, biting Perry’s knee and triggering a chaotic chain of events. In the struggle, Perry fires a tranquilizer dart at Koontz, disabling the helicopter’s controls and letting Cubby slip free.
Cubby races back toward Devils Thumb as Sean and Jessie push forward, following the trail of wreckage from Jake’s plane. They finally find Jake, who has managed to signal for help with a flare. In a tense moment of courage and trust, Jessie lowers Sean on a rope to reach his father, and Cubby suddenly comes to the rescue, pulling the rope and helping bring Jake and Sean back to safety.
As the family is brought to safety, Charlie arrives to complete the rescue. Perry and Koontz, now separated from their helicopter and their prize, must trek on foot through the wilderness, while the Barnes family, grateful and exhausted, returns Cubby to the wild. Cubby reunites with a new polar bear family, leaving behind the humans with a sense of relief and a new lease on life in the rugged Alaskan frontier.
