A gigantic meteor enters Earth's orbit and begins to disintegrate, showering the entire planet with debris.
A long-period comet's orbit is determined to be crossing directly in the path of Earth's orbit. All of the world's nuclear states fire their missiles at the comet, but pieces of the comet continues to strike the Earth, contaminating the groundwater and causing millions to become sick.
The story follows David Dmatti (Joe Lando) as he searches for his wife Kate (Claudia Christian) and sick daughter Allison (Madison McLaughlin). They were initially quarantined in the Las Vegas Valley. David, finds and revives Lynn (Cooper Harris) at a gas station and brings her with him to Las Vegas.
When they arrive, they learn most of the city was destroyed and the quarantined were transferred to Los Angeles. David is also able to get an antidote for the mysterious illness. When it is discovered that the largest comet fragment will most likely hit Los Angeles, a panicked evacuation is begun. The problem is the quarantined are left behind. While trying to rescue David's family, Lynn dies, leaving enough antidote for David's daughter. He and his family are soon reunited, just as the final fragment strikes the city.
