Dr. Lawrence "Larry" Angelo works for Virtual Space Industries and runs experiments using psychoactive drugs and virtual reality to enhance cognitive performance, using chimpanzees as test subjects. Angelo has benevolent aims, but VSI is funded by "The Shop," a clandestine group hoping to turn chimps into expendable soldiers. One of the chimps, gifted with new intelligence, warfare training, and increased aggression, successfully escapes. Although tempted to abandon his work in frustration, Angelo later decides to recruit intellectually disabled greenskeeper Jobe Smith as a human test subject, telling the man he will become smarter. Angelo redesigns the intelligence-boosting treatments to remove the "aggression factors" used in the chimpanzee experiments. Jobe's intelligence is successfully enhanced, and he also develops psychokinesis and telepathy. He continues training at the lab until an accident forces Angelo to abort the experiment.
The project director, Sebastian Timms, keeps tabs on the progress of the experiment and secretly swaps Angelo's new medications with the old Project 5 supply, reintroducing an increase in aggression. When Jobe invites his new lover Marnie to the lab to engage in virtual reality cybersex, he accidentally erases her mind in the process. Jobe continues the treatments on his own and soon begins killing the people who mistreated him in the past, as well as the abusive father of his teenage friend Peter. Angelo learns the medications have been swapped and confronts Jobe. The lawnmower man captures him and declares his plan to reach an ultimate stage of evolution by becoming a being of "pure energy" existing in the VSI computer mainframe, connecting to all computer systems of the world afterward. He promises his "birth" will be signaled by every telephone on the planet ringing simultaneously.
The Shop sends a team to capture Jobe, but with his new abilities he scatters their molecules. Jobe uses the lab equipment to enter the VSI mainframe and become a digital being, leaving his body behind like a husk. Angelo remotely accesses the VSI computer, encrypting connections to the outside world and trapping Jobe in the mainframe. As Jobe searches for an unencrypted network connection, Angelo sets bombs to destroy the building. Feeling responsible for what happened to Jobe, Angelo enters virtual reality to attempt reasoning with him one last time. Jobe overpowers Angelo and crucifies his digital body. Peter runs into the building and Jobe realizes he is in danger from the bombs. Still caring for the boy, he allows Angelo to leave the mainframe so he can rescue Peter. After Jobe forces a security door to open, Angelo and Peter escape the building. Jobe finally escapes through a maintenance line just before the building is destroyed by multiple explosions.
Angelo is later at home with Peter and the boy's mother Carla. The telephone rings, followed by the noise of a second telephone ringing elsewhere, followed by hundreds of telephones ringing all around the globe.
Pierce Brosnan as Dr. Lawrence Angelo
Jeff Fahey as Jobe Smith
Jenny Wright as Marnie Burke
Geoffrey Lewis as Terry McKeen
Jeremy Slate as Father Francis McKeen
Dean Norris as The Director
Austin O'Brien as Peter Parkette
Troy Evans as Lt. Goodwin
Rosalee Mayeux as Carla Parkette
Mark Bringelson as Sebastian Timms
Ray Lykins as Harold Parkette
Colleen Coffey as Caroline Angelo
adapted from an original screenplay entitled "CyberGod". The title comes from a 1975 short story by Stephen King.