Melanie Parker, an architect and mother of Sammy, and Jack Taylor, a newspaper columnist and father of Maggie, are both divorced. They meet one morning when overwhelmed Jack is left unexpectedly with Maggie and forgets that Melanie was to take her to school. As a result, both children miss their school field trip and are stuck with the parents. The two adults project their negative stereotypes of ex-spouses on each other, but end up needing to rely on each other to watch the children as each must save his job. Humor is added by Sammy's propensity for lodging objects in his nose and Maggie's tendency to wander.

Complete strangers stranded at a remote desert motel during a raging storm soon find themselves the target of a deranged murderer. As their numbers thin out, the travelers begin to turn on each other, as each tries to figure out who the killer is.

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.