Najstnik Leo Beiderman se pridruži šolskemu astrološkemu krožku v upanju, da ga bo opazila lepa sošolka Sarah. Še najmanj pričakuje, da bo odkril nekaj, kar bo pretreslo svet. Fotografija, ki jo posname z malim teleskopom, prikazuje komet, za katerega znanstveniki zatrjujejo, da bo trčil z Zemljo. Zdaj vsi upi človeštva ležijo v posebnem vesoljskem plovilu, ki naj bi pristalo na kometu in ga uničilo, še preden bi prišlo do katastrofe. Toda bolj ko se bliža usodni dan, bolj napeti so odzivi ljudi.
Journalist Jenny Lerner is assigned to look into the background of Secretary Alan Rittenhouse who abruptly resigned from government citing his wife's ill health. She learns from his secretary that Rittenhouse was having an affair with someone named Ellie but when she confronts him, his strange reaction leads her to reconsider her story. In fact, a comet, discovered the previous year by high school student Leo Biederman and astronomer Dr. Marcus Wolf, is on a collision course with the Earth, an Extinction Level Event. A joint US-Russian team is sent to destroy the comet but should it fail, special measures are to be put in place to secure the future of mankind. As the space mission progresses, many individuals deal with their fears and ponder their future.