April Wood is an eleven-year-old girl living a quiet, lonely life with her father, Edmund, a university scientist who researches weather patterns. April's mother died in a car accident when April was four, and Edmund has been emotionally distant ever since. April spends most of her time befriending urban foxes in the backyard and is socially isolated at school. When a letter arrives from the Norwegian government offering Edmund a six-month posting to monitor weather data on Bear Island, a small, uninhabited Arctic island with only a weather station, April is thrilled. Her grandmother, Granny Apples, protests that the island is dangerous, but Edmund reassures everyone that no polar bears remain there. On April 1, they fly to Norway and board a cargo ship for Bear Island.
On the ship, April meets Tör, the captain's son, a boy a few years older than her. Tör warns her that the island is wild and dangerous but is impressed by her gift with animals. Before they part, he gives April his phone number for emergencies. The island proves barren and fog-shrouded, dotted with mountains, lakes, and snow. Their new home consists of two wooden cabins: one for living and one for Edmund's meteorological work, equipped with a satellite phone. That evening, Edmund gives April her late mother's silver watch and the Norwegian word
friluftsliv, or "open-air life," telling her she reminds him of her mother, who had a rare affinity with animals. Standing at her window under the bright Arctic sky at 11 p.m., April spots something big and loping on the horizon.
Edmund disappears into the weather cabin each day, leaving April to a solitary routine of self-directed study and afternoon explorations. She secretly searches for what she believes is a polar bear. Edmund explains that bears once traveled to the island via ice caps from Svalbard, about 250 miles north, but the melting of the ice has made the journey impossible. April eventually discovers Walrus Bay, a remote cove with the ruins of an old whaling station and an upturned boat. There she hears a deep noise: the unmistakable sound of an animal in pain.
Across the beach stands a magnificent but desperately thin polar bear with matted fur and visible ribs. Through binoculars, April sees that his front left paw is tightly wrapped in blue plastic and fishing net, swollen to twice its normal size. She takes her father's Swiss Army knife, determined to free him. Over the following days, she brings food to Walrus Bay, patiently building trust. She names him simply "Bear," reasoning that wild animals do not need human names. After days of offering food, practicing calm breathing, and sitting perfectly still, she crouches beside him and painstakingly cuts the net and plastic away. When freed, Bear roars so powerfully the earth trembles.
April visits Bear daily, and their greeting ritual becomes a mutual roar. She confides in him about her loneliness and grief, admitting her wish that Edmund would find a new partner and, more vulnerably, her own longing for a mother figure. These are secrets she has never spoken aloud, and Bear listens with intuitive sensitivity, becoming her closest confidant. Edmund and April share a rare warm moment during the midnight sun ceremony, making wishes and drinking hot chocolate. Edmund reveals that the next day is April's mother's birthday, and April nearly tells him about Bear but stops herself. Their connection frays when Edmund snaps at April for accidentally damaging a logbook. She runs to Walrus Bay, where Bear's joyful greeting erases the hurt.
When April twists her ankle, Bear crouches low and lets her ride on his back. He takes her to his home, a dark cave on the smallest mountain, where she senses he has been alone for years. As weeks pass, Bear's health is restored by April's food and his own resumed hunting. His coat turns brilliant white and he radiates vitality. Together they explore every corner of the island, and Bear teaches April to read the wind and attune herself to the natural world. During the perpetual daylight of the midnight sun, April's watch stops. When the period ends and darkness returns, the watch resumes, and April recognizes their remaining time is running out.
Bear leads April to the summit of the tallest mountain. Facing north toward Svalbard, his deep sadness becomes visible. Through his body language and her own intuition, April pieces together his story: He arrived as a young cub with his mother via the ice caps. The ice melted, trapping them; his mother eventually died, and Bear has been alone ever since. April presses Edmund about the climate data from his logbooks. He confirms that a dramatic temperature spike seven years earlier caused the last ice to melt, meaning Bear has been stranded for seven years. She reveals Bear's existence and confesses to feeding him their provisions, but Edmund concludes she has invented an imaginary friend due to isolation.
Devastated, April resolves to act alone. She will repair the upturned boat at Walrus Bay and sail Bear north to Svalbard, where thousands of polar bears live. She calls Tör on the satellite phone under the pretense of a school report and learns to set the compass due north toward Svalbard. Over the following weeks, she secretly repairs and provisions the boat.
Then Edmund receives word that his replacement is arriving the next day, weeks early, and agrees to leave without consulting April. She is furious, confronting him with a roar so loud it shocks him, accusing him of never listening and of being so consumed by grief that he cannot see his own daughter. That night, she writes a goodbye note saying she loves him and that Bear is real, leaves it outside his door with a mug of hot chocolate, and climbs out her window, forgetting the satellite phone.
At Walrus Bay, Bear pushes the boat into the surf, and they set out into the dark night. A ferocious storm tears the boat apart. April is pulled underwater by freezing currents and loses consciousness. Bear swims to her, pulls her from the water in his jaws, and holds her afloat until rescue arrives.
April wakes aboard the same cargo ship that originally brought them to Bear Island, with Edmund at her side. Tör, recalling her phone call, guessed her destination and helped direct the search. April finds Bear chained in the hold; the captain wants to kill him as a dangerous animal. She throws herself in front of Bear, declaring that the captain must kill her first. Edmund steps forward to support her, acknowledging that his disbelief was wrong. He tells April she is just like her mother and that her heart never lies, and the two reconcile. Tör appeals to his father's knowledge of retreating sea ice, and April insists that helping even one bear matters. The captain relents, citing concern for his son's future, and orders the ship north to Svalbard.
Svalbard appears as a dazzling wilderness of glaciers and light, and Bear quivers with recognition. On shore, Lisé, a young woman from the Polar Institute, a Norwegian government conservation organization, promises to monitor Bear's health and reintegration. April gives Lisé the last jar of peanut butter and instructions on Bear's favorite spots to be stroked. As the ship's horn sounds, April kisses Bear, tells him she loves him, and watches through tears as he grows smaller on the receding shore. Bear rises on his hind legs and sends one final roar across the waves.
On deck, Edmund holds April as she sobs, promising to become a real father. He proposes they move to the seaside near Granny Apples and that he will develop compostable alternatives to plastic. Tör promises to send photos of Bear. April declares that when she is old enough, she will move to Svalbard and work at the Polar Institute. Standing at the railing, she opens her mouth and lets out a full polar bear roar that carries across the waves. On the distant shore, Bear receives it like one last embrace, then bounds off to begin his new life.