Computer-store employee Karl Hochman (Ted Marcoux) is secretly "The Address Book Killer" - he steals people's address books and kills everybody listed within, as well as the book's owner. When Terry Munroe (Karen Allen) accidentally leaves her address book behind at the store, Karl is in pursuit - but he instead ends up in a car accident. While being CAT scanned the hospital is struck by lightning and Karl's mind is converted to electrical impulses turning him into a near-omniscient computer virus that can also travel via electrical lines. He begins murdering Terry's friends via household items such as microwave ovens and hair dryers. Fortunately, Terry's son Josh figures out what's going on, and the pair enlist genius hacker Bram Walker to fight the "Karl virus."