Synopsis
Structural engineer John Garrity lives in Atlanta, Georgia with his estranged wife, Allison, and their diabetic son, Nathan. He returns home to watch the near-earth passing of a recently-discovered interstellar comet named "Clarke", along with his family and neighbors.
While at the grocery store, John receives an automated DHS message saying that he and his family have been selected for emergency sheltering. He then returns home just as a comet fragment is seen entering the atmosphere on live television. Previously expected to land in the ocean near Bermuda, the fragment instead strikes Tampa, Florida, vaporizing most of the state. John then receives a call with instructions to head to Robins Air Force Base for an evacuation flight, as Clarke is on a direct collision course with Earth and the entire planet will be bombarded with hundreds of fragments within the next two days in a cataclysmic event, with one fragment large enough to cause an extinction-level event. John, Allison, and Nathan pack up and flee, unable to take anyone else with them as they would be denied boarding.
At Robins, Nathan's insulin gets left behind in the car. When John goes to retrieve it, Allison is escorted off the base after Nathan's medical condition is discovered, disqualifying him. John returns and boards a plane but quickly jumps off upon realizing Allison and Nathan were probably left behind. As John exits the base, a panicked mob breaks in, destroying several evacuation planes when gunfire ignites jet fuel. Returning to the car, John finds Allison's note saying she and Nathan are going to her father's home in Lexington, Kentucky. After getting medical supplies from a looted store, Allison and Nathan get a ride from Ralph and Judy Vento, only for Ralph to kidnap Nathan, to Judy's dismay, in order to use him and the wristbands to board a flight.
John hitches a ride on a truck where a young man named Colin says is headed to Osgoode, Ontario, where private planes are flying to Greenland, the apparent evacuation site. However, another man attempts to take John's wristband, causing the truck to crash and kill Colin, and John is forced to kill the man in self-defense. At another airport, the Ventos attempt to pose as Nathan's parents, but are arrested when the soldiers quickly discover that Nathan is not theirs. Allison and Nathan are reunited shortly after at a nearby FEMA camp. The following morning, John learns that millions have perished in global impacts and that the largest fragment will make impact in approximately 24 hours.
Stealing a car, John reaches his father-in-law, Dale's house, and Nathan and Allison arrive shortly after. The family learn about a complex of underground bunkers near Thule Air Force Base in Greenland where the evacuees are being sent. The family has just enough time to reach Osgoode, so John and Allison decide to go while Dale elects to stay behind and gives them his truck. In Upstate New York, the family is caught in a traffic jam. As a