After years of increases in the greenhouse effect, havoc is wreaked globally in the form of catastrophic hurricanes, tornadoes, tidal waves, floods and the beginning of a new Ice Age. Paleoclimatologist Jack Hall tries to warn the world while also shepherding to safety his son, trapped in New York after the city is overwhelmed by the start of the new big freeze.

Strange phenomena surface around the globe. The skies ignite. Terror races through the world's major cities. As these extraordinary events unfold, it becomes increasingly clear that a force of incredible magnitude has arrived. Its mission: total annihilation over the Fourth of July weekend. The last hope to stop the destruction is an unlikely group of people united by fate and unimaginable circumstances.