David Lightman (Broderick) is a smart high school student and computer hacker that at first limits himself to changing his and a girl whom he likes a lot, Jennifer's (Sheedy) grades from failing to passing grades: Lightman being smart but not motivated at school. A little while later David uses his IMSAI 8080 computer to dial many phone numbers and finds a backdoor into a NORAD war games simulation computer called WOPR (nicknamed the "Whopper"). At first David is looking for new computer games to download and play and believes that the WOPR is actually the computer of a company that makes new computer games. After finding a list of games on the computer decides to play a game. WOPR (who is an Artificial Intelligence computer) asks David for a password and after doing some research on the computer's creator Professor Steven Falken he guesses that the password is named after the creator's dead son, Joshua. After logging in using the correct password, W.O.P.R. believes David to actually be Dr. Falken whom the computer had believed to be dead. The computer (which David now calls "Joshua") asks him if he would like to play a game. David selects the game "Global Thermonuclear War". Doing so starts off a series of events that will end up taking the World into World War III unless it is stopped.