A year after a comet is discovered by 14-year-old amateur astronomer Leo Biederman (Elijah Wood), it is announced that the object's trajectory is leading it on a collision course with Earth. American President Tom Beck (Morgan Freeman) calls for calm while experienced astronaut Spurgeon Tanner (Robert Duvall) heads into space in an attempt to destroy the comet before it hits. The mission is covered on television by reporter Jenny Lerner (Tea Leoni), who discovers that astronomer Marcus Wolf knew the comet was a threat a year earlier, but died in mysterious circumstances before he could make his findings known.