Press Enter has four principal characters: Charles Kluge, Detective Osbourne, Victor Apfel, and Lisa Foo. The word kluge comes from German, meaning clever. It is, as the story explains, used by computer hackers to mean someone who is tricky. Although Kluge is found dead at the story's start, his bewilderingly extensive looting of data from computers throughout the country forms the background for the story's events. Really named Patrick William Gavin, Kluge chose a computer name for himself, destroyed records of himself, and lived as an extension of his computer empire. When he explores his notion of a rational mind created by linking millions of home computers, something strikes back through his own computer, murdering him.

Police detective Osbourne is suspicious of Kluge/Gavin's death from the start. He senses that it is murder even though it appears to be suicide. A dogged investigator, he keeps the case...