Senior school student David Lightman (Matthew Broderick) has a knack for hacking. However, he initiates a bang with global proportions and taps into the Defense Department's war computer while attempting to hack a computer system to play with video games! With his girlfriend (Ally Sheedy) and a wizardly computer ace (John Wood), David has to race against time to outwit his competitor. . .and avert a nuclear Armageddon.