Psychopharmacologist Siegel (Fire in the Brain, 1992) hosts his readers on a trip through the minds of the mentally ill, and in some cases makes the journey himself, providing a travelogue. Siegel's greatest virtue is his ability to understand his subjects' paranoia, and he explains how he often became ``infected'' with it himself, sometimes accidentally and sometimes by purposefully repeating his subjects' experiences, such as the train trip of Mario N., who had a cocaine-related paranoid episode on a train that led him to shoot his sister and allow his infant nephew to die from dehydration; listening to police surveillance tapes, Siegel re-creates the conditions of sleep and sensory deprivation that Mario experienced. Siegel does not shy away from personal asides during these stories, nor from the occasional wisecrack (in a disclaimer in the introduction he calls this humor ``a defensive projection''). He profiles a graduate student named Mark Steiner who invites him to see Hitler's brain in a basement laboratory, only to reveal that he has programmed a computer to respond to questions exactly as Hitler--whose paranoid pathology Siegel convincingly describes--would have. Eddie Tolman wears underwear made of aluminum foil to defend himself against the electronic rays that he believes are being aimed at him, a belief that most likely stems partly from the accidental deaths of his pet hamsters when he was a child. Elderly Lillian Rush believes that her dentist has implanted devices in her teeth that cause her to hear whispering noises. Siegel also reports on a series of subjects experiencing paranoid reactions from cocaine use: some feel bugs on them, others see worms, dwarves, and sadistic cats attacking. This is the least interesting group, since their experiences are all fairly similar. Scary and often gruesome, but fascinating.