A solitary figure, Larsen, Hagan Beggs, hurries across an arctic landscape to his tent and sends an emergency radio signal, trying to contact colleagues on the ship 'Morning Rose', but he is killed before he can transmit any useful information.
The Morning Rose carries a multinational expedition of United Nations scientists to Bear Island to study climate change. Leading the team are German scientists Gerran and his deputy Hartman, and the group also includes Norwegian psychiatrist Lindquist and the laconic Pole Lechinski Lechinski. American biologist Frank Lansing Lansing joins the boat, where he is reunited with his friend Smithy and former colleague Rubin. Lansing's suspicions are awakened when his belongings are searched shortly after arrival.
The expedition reaches Bear Island, home to a NATO base and the site of a former U-boat station. German colleagues Jungbeck and Heyter inform them that Larsen is missing. Gerran forbids access to the old U-boat base, but Lansing’s interest grows—his father was a U-boat commander who died there.
Lansing and Rubin disobey orders and venture toward the area near the U-boat base; an unknown saboteur triggers an avalanche with explosive charges, killing Rubin. Later, Lansing discovers an underwater entrance to the base, where he finds his father’s submarine with his remains still inside. He also finds signs that others have visited the base recently, and he grows suspicious that Jungbeck and Heyter are involved.
Lansing and Smithy decide to seek help at the NATO base, and although their snowmobile is sabotaged, they both survive the ensuing explosion. Meanwhile, Lindquist finds a message left by Larsen, revealing that he had been a Norwegian agent and confirming that Jungbeck and Heyter are neo-Nazis controlled by a third expedition member codenamed Zelda. Lansing takes Lindquist to the U-boat, where they uncover crates marked as explosives, but they discover one opened crate that is actually filled with gold.
Back at the base, a series of suspicious incidents continue: the radio mast collapses, fatally wounding Lechinski Lechinski, and an explosion destroys the electrical generator, apparently killing Smithy. Lansing suspects Jungbeck and Heyter and they are arrested and locked up. The next morning, Lansing and Lindquist head out from the base, but Jungbeck and Heyter are released by Zelda and give chase. While lying in wait for their pursuers, Lansing realizes that Hartman has given him an unloaded rifle, and that he may be Zelda. Jungbeck and Heyter track them down, but Lansing eliminates them.
Lansing returns to the U-boat and finds that the gold has been removed. He reunites with Smithy, who is alive after all, and Smithy makes a bid to secure the gold for himself. Hartman waits to depart with the research boat and the gold, unaware that his henchmen are dead. A conflicted Gerran—cleared of Nazi sympathies but ashamed of not doing more to oppose them—wants to return the gold to Norway as an act of contrition and confronts Hartman at the harbor, but is shot and disabled.
Smithy disarms Hartman and takes him onto the boat, while Lansing pursues. Smithy is confronted by Hartman and killed, but Lansing reaches the boat, boards it, and kills Hartman.
The SS logbook recovered by Lansing reveals that his father refused to hand over the gold to the SS in 1945, and had been executed along with his crew. At the burial of his father, Smithy and Lechinski are present, and Lansing finds closure by embracing Lindquist.
