While fixing a satellite in orbit, the Space Shuttle Atlantis was destroyed by a meteor shower, killing the entire crew. Meteorites then bombarded New York City and several other parts of the world, and NASA discovered that an asteroid the size of Texas, traveling at 22,000 miles per hour, would collide with Earth in 18 days, effectively destroying the planet. The scientists at NASA - in cooperation with the Russian, Japanese and French space agencies - planned to detonate a nuclear bomb at a precise point under the asteroid's surface which will split it in two, and cause it to miss the Earth. However, the bombs needed to be planted at least 800 feet below the surface within eight hours of landing, and no later than four hours before the Earth impact. The mission is not revealed to the public, fearing panic.

NASA located Harry Stampehr, regarded as the world's best deep-core oil driller, to train NASA astronauts for the drilling. When invited to NASA, Harry brought his 20-something daughter Grace to keep her away from A.J., a young, rambunctious member of his crew who, he has just discovered, has been sleeping with her. Harry was disappointed and infuriated because he did not want his daughter to marry an oil driller like himself or remain in the blue collar life.

Head of NASA Dan Truman informed Harry of the dire situation. After hearing Truman's grim scenario, Harry asked if the only job will be to drill the hole and put the bombs down. Truman assures Harry that the only job will be to drill, and no spacewalks or other astronaut duties would be involved, and Harry decided to recruit his own oil-drilling crew for the job to ensure it is done properly.

Harry detonates the bomb exactly at the deadline, causing the asteroid to split in two and miss the Earth by 400 miles, at the cost of his own life. In the wake of one of the massive pieces is the Freedom, heading for home. On the ground, celebrations take place around the world that the asteroid threat is gone. The remaining men & women of Freedom and Independence return to Earth as heroes. As the Freedom touches down at KSC, it is met with the fire crews and families of the astronauts. A.J. reunites with Grace; Chick is met by his son and former wife; Rockhound is met by Molly Mounds - a stripper he had met the night before leaving on the mission; Col. Sharp meets with Grace and offers his gratitude - and admiration - for her father's bravery & selflessness.