The Earth is in peril after a series of bizarre incidents, including powerful electrical storms and erratic behavior in creatures that use the planet's magnetic field for navigation. Dr. Josh Keyes, a brilliant scientist, discovers that these are symptoms of a much larger problem: the planet's core has stopped rotating. This cessation of movement has disrupted the Earth's magnetic field, which shields the surface from deadly solar radiation. Without the field's protection, the planet will soon become uninhabitable. To avert global catastrophe, Keyes proposes a risky mission: to reignite the Earth's core by detonating nuclear devices deep within it.

A team of experts is rapidly assembled: Keyes himself, a geophysicist; Major Rebecca Childs, a talented space shuttle pilot; Dr. Conrad Zimsky, the government's arrogant geophysicist; Dr. Ed Brazzleton, the eccentric inventor of a revolutionary drilling vehicle named "Virgil"; and two astronauts, Serge Leveque and Theodore Donald 'Rat' Finch, who is skilled in computer hacking. The extraordinary group embarks on an unprecedented voyage to the planet's center aboard the Virgil, which is equipped to bore through the Earth's layers using a powerful laser. As they travel deeper into the Earth, the team must overcome a series of technical and environmental hazards, while above ground, the world continues to suffer from the effects of the failing magnetic field.