Climatologist Jack Hall has been researching the effects of global warming and begins to see worrying patterns that indicate a massive shift in the climate could be about to happen. His research suggests that melting polar ice caps could lead to a shutdown of the North Atlantic current, which keeps the northern hemisphere warm. Despite his warnings to UN officials and U.S. government, his concerns are largely dismissed as speculative. However, as a series of extreme weather events start to occur around the world, it becomes clear that his predictions are becoming a reality. Superstorms develop, bringing devastating weather, including hailstorms in Tokyo, hurricanes in Hawaii, and tornadoes in Los Angeles.

Meanwhile, Jack's son, Sam, is in New York City for an academic competition when the catastrophic weather hits. New York is struck by a massive tidal surge before being submerged in a deep freeze, trapping Sam and his friends. As conditions worsen and the temperature plummets, Sam and his companions take refuge in the New York Public Library, trying to survive the unparalleled cold. They gather food and supplies, burn books to stay warm, and struggle to keep hope alive in the face of seemingly insurmountable odds. Concurrently, realizing the full extent of the unfolding disaster, Jack embarks on a daring and treacherous trek from Washington, D.C. to Manhattan to find his son, navigating the frozen wasteland that the northern hemisphere is rapidly becoming.