After a series of bizarre incidents around the globe that are tied to fluctuations in the Earth's electromagnetic field, a group of scientists embarks on a dangerous mission. At the center of this effort are Dr. Josh Keyes (played by Aaron Eckhart), a seasoned geology professor, and Conrad Zimsky (brought to life by Stanley Tucci), an arrogant researcher. Together, they uncover a chilling truth: the Earth's molten core is gradually coming to a halt. Should this continue, the electromagnetic field that protects our planet will vanish, leaving the surface exposed to relentless solar radiation that could incinerate everything in sight.
The narrative kicks off during a business meeting where a young man loses consciousness, prompting a disturbing sequence of events as birds outside begin to collide with buildings. Shortly thereafter, Dr. Josh Keyes is approached at the University of Chicago by government officials and taken to a secure facility. Here, he meets an old colleague, Dr. Serge Leveque (Tchéky Karyo), a nuclear weapons expert, uncovering a gruesome sight: multiple bodies all deceased at the same moment. Their quick analysis leads them to discover that all victims had pacemakers, impressing General Purcell (Richard Jenkins) with their swift deduction.
Amidst these troubling happenings, the space shuttle Endeavor finds itself off-course, hurtling towards downtown Los Angeles. Navigator Major Rebecca "Beck" Childs (Hilary Swank) deftly avoids disaster by landing in the L.A. River after a malfunction attributed to the strange magnetic anomalies.
Determined to save the planet, Keyes, Leveque, and Zimsky enlist the help of Ed "Braz" Brazzelton (Delroy Lindo), who introduces a high-speed drilling technique utilizing powerful lasers. They also develop a resilient material, "unobtainium," capable of withstanding immense pressure deep within the Earth. Despite their contentious history, Braz agrees to collaborate with Zimsky for the greater good, while Purcell assures him of necessary funding.
Keyes works on a method to visualize their path using x-rays, and an expert hacker nicknamed "Rat" (DJ Qualls) is recruited to keep the public out of the loop regarding the potential crisis. As the team prepares for their descent in a newly designed vessel dubbed Virgil, they face immediate challenges when they crash-land in a massive geode filled with amethyst, leading to the untimely death of Iverson (Bruce Greenwood).
As they delve deeper, tragedy strikes when Leveque sacrifices himself to ensure the mission can proceed. Facing insurmountable odds, the crew must execute a complex plan involving precision detonations to reignite the core. The looming threat of losing Zimsky hovers over them, and as the countdown to the explosions ticks away, Keyes must make harrowing decisions.
Ultimately, their daring plan is successful, managing to restart the core just before escaping a devastating blast. Though they find themselves stranded on the ocean floor post-mission, military forces trace their location through whale songs. Amidst recovery and revelations, Rat exposes the truth about the now-infamous Project DESTINI, honoring the sacrifices made by their fallen comrades, ensuring that their heroic efforts remain etched in history.
