The "Biedermann Comet" is hurtling towards the Earth, dealing a fatal blow to humanity. The authorities acted urgently and worked out the best plan - astronaut Tanner (Robert Duvall) would fly the "Messiah" spacecraft to the comet, place a pre-prepared nuclear bomb on the comet and detonate it to break it into pieces or change its orbit. Tanner completed the mission heroically, but found that it did not achieve the expected results. The comet broke into two parts, one large and one small, and approached the Earth step by step. The authorities quickly took the final action and used the "Noah's Ark" plan to save some Earth species, including humans. This is a secret underground shelter where only a few people can avoid the catastrophe and rebuild the world after the disaster is over. The smaller part of the comet has already hit the Earth, causing landslides and cracks, a scene of the end of the world. The degree of destruction brought to the Earth by the large comet that followed will be far beyond people's imagination, and humans who have turned the tide have entered the countdown moment.