Prof. Lehman discovers in his Mexican observatory earth is about to be hit by asteroid 114 Kassandra, thrice the size of Mt. Everest, more than the meteor which ended the dinosaur age, preceded by a minor meteor shower. Alas on the road back he dies in a car crash. His assistant Imogen has a hard time getting his data home, where the military HQ is inaptly advised by Dr. Nate Chetwyn. LAPD detective Jack Crowe is set up for his wife's murder by his dirty ex-partner Calvin Stark, who kidnaps his daughter Jenny, determined to make him suffer. That includes Jack's dad, the sheriff in home town Taft, trying to keep order and organize help as the first debris hits cause damage. Life soon breaks down worldwide, in panic and looting after numerous hits. The military uses its rocket arsenal.

Following an unparalleled series of meteor fireballs plummeting toward Earth, a renowned scientist, his assistant, and an on-target conspiracy theorist race against time to expose a government cover-up, reveal the truth, and prevent a massive meteor from destroying the planet.