Short answers, pulled from the story.
The Dungeon Master: The Disappearance of James Dallas Egbert III is a 1984 book by private investigator William Dear. It recounts the 1979 steam tunnel incident at Michigan State University, in which sixteen-year-old student James Dallas Egbert III disappeared, and presents Dear's argument that the news media misrepresented what actually happened.
James Dallas Egbert III was a sixteen-year-old child prodigy enrolled at Michigan State University. He was dealing with intense academic pressure, drug addiction, and personal issues at the time of his 1979 disappearance. He died by self-inflicted gunshot wound in 1980, less than a year after the steam tunnel incident.
According to William Dear's account in The Dungeon Master, Egbert entered Michigan State University's utility tunnels with the intent of committing suicide. After that attempt, he went into hiding rather than coming forward, which is what prompted the search.
Private investigator William Dear, who was unfamiliar with Dungeons and Dragons, suggested Egbert may have entered the tunnels to play a live-action version of the game after learning Egbert had played it. The news media treated this theory as fact, which sparked intense controversy over the psychological effects of role-playing games.
Dear had made a personal promise to James Dallas Egbert III not to reveal the true circumstances of his disappearance. He kept that promise for four years after Egbert's death in 1980, finally publishing The Dungeon Master in 1984 to correct the public record.
After several weeks in hiding, Egbert gave himself up to William Dear. In 1980, less than a year after the 1979 steam tunnel incident, he died by self-inflicted gunshot wound.