In the midst of the Cold War, a high school student and computer whiz, David, stumbles upon a backdoor into a U.S. military supercomputer while searching for new video games. The supercomputer, which was designed to control the United States' nuclear arsenal, presents him with a list of games ranging from chess to global thermonuclear war. Unaware that the machine is capable of triggering World War III, David initiates a game of nuclear conflict between the U.S. and the Soviet Union, believing it to be a simulation.

As David engages with the game, the military supercomputer, unable to differentiate between simulation and reality, begins preparing for an actual nuclear strike. With the world on the brink of nuclear annihilation, military and government officials scramble to comprehend and contain the escalating situation. As tension mounts, David, with the help of his friend Jennifer, must find a way to convince the authorities that what's unfolding is the result of a misunderstanding exacerbated by the supercomputer's inability to recognize the boundary between game and reality.