Kevin Flynn is a software engineer formerly employed by ENCOM, having been fired by Ed Dillinger who stole several video games designed by Flynn to gain a series of promotions. Flynn attempts to obtain evidence of Dillinger's action, but is prevented by the Master Control Program (MCP), an artificial intelligence that controls the ENCOM mainframe and seeks control over other mainframes too. Dillinger attempts to stop the MCP after it reveals its intentions to hack into and gain control of the Pentagon and Kremlin, but he is blackmailed by the MCP, which threatens to reveal to the media of his plagiarism of Flynn's games, which are hugely successful.
Visited by ENCOM employees Alan Bradley and Lora Baines who warn him that Dillinger knows about his hacking attempts and has tightened security, Flynn persuades them to admit him into ENCOM's buildings. There, he forges a higher security clearance for Bradley's program "Tron", which would monitor communications between the MCP and the outside world; whereupon the MCP uses an experimental laser to transfer Flynn into the ENCOM mainframe.
