Kevin Flynn is a leading software engineer, formerly employed by large technology corporation ENCOM. He now runs a video game arcade, and attempts to hack into ENCOM's mainframe system; however, ENCOM's Master Control Program (MCP) halts his progress. Within ENCOM, programmer Alan Bradley and his girlfriend, engineer Lora Baines, discover that the MCP has closed off their access to projects. When Alan confronts the senior executive vice president, Ed Dillinger, Dillinger says the security measures are an effort to stop outside hacking attempts. However, when Dillinger privately questions the MCP through his computerized desk, he realizes the MCP has expanded into a powerful virtual intelligence and has been illegally appropriating personal, business, and government programs to increase its own capabilities. As Dillinger rose to the top of ENCOM by presenting Flynn's games as his own, the MCP blackmails Dillinger by threatening to expose his plagiarism if he does not comply with its directives.