Dr. Adrian Helmsley, part of a worldwide geophysical team investigating the effect on the earth of radiation from unprecedented solar storms, learns that the earth's core is heating up. He warns U.S. President Thomas Wilson that the crust of the earth is becoming unstable and that without proper preparations for saving a fraction of the world's population, the entire race is doomed. Meanwhile, writer Jackson Curtis stumbles on the same information. While the world's leaders race to build "arks" to escape the impending cataclysm, Curtis struggles to find a way to save his family. Meanwhile, volcanic eruptions and earthquakes of unprecedented strength wreak havoc around the world.

After years of unabated global warming, the greenhouse effect is wreaking havoc all over the globe in the form of catastrophic hurricanes, tornadoes, tidal waves, floods and, most ominously, the beginning of the next Ice Age. Paleoclimatologist Jack Hall tries to save the world while also shepherding to safety his son Sam, who was in New York when the city was overwhelmed by the beginnings of the new big freeze.

When a freighter is viciously attacked in the Pacific Ocean, a team of experts -- including biologist Niko Tatopoulos and scientists Elsie Chapman and Mendel Craven -- concludes that an oversized reptile is the culprit. Before long, the giant lizard is loose in Manhattan, destroying everything within its reach. The team chases the monster to Madison Square Garden, where a brutal battle ensues.

On July 2, a giant alien mothership enters orbit around Earth and deploys several dozen saucer-shaped "destroyer" spacecraft that quickly lay waste to major cities around the planet. On July 3, the United States conducts a coordinated counterattack that fails. On July 4 the a plan is devised to gain access to the interior of the alien mothership in space in order to plant a nuclear missile.

Two very different men join forces to unravel the mystery of a "Stargate," an ancient human transmitter, discovered in the Egyptian desert. Once activated, it enables scientists and the military to travel light years from earth, to a strange and alien world, where the visitors must overcome an enigmatic ruler.