Kevin Kline and Glenn Close star as Harold and Sarah Cooper, a couple whose marital troubles are put on hold while they host an unhappy reunion of former college pals gathered for the funeral of one of their own, a suicide victim named Alex.
High School student David Lightman (Matthew Broderick) has a talent for hacking. But while trying to hack into a computer system to play unreleased video games, he unwittingly taps into the Defense Department's war computer and initiates a confrontation of global proportions! Together with his girlfriend (Ally Sheedy) and a wizardly computer genius (John Wood), David must race against time to outwit his opponent.
The film portrays a fictional nuclear war between NATO forces and the Warsaw Pact that rapidly escalates into a full scale exchange between the United States and the Soviet Union, focusing on the residents of Lawrence, Kansas, and Kansas City, Missouri, as well as several family farms situated next to nearby nuclear missile silos.