From 1990 to 1995, conducting DEA-approved clinical research, Dr. Strassman injected 60 volunteers with DMT, one of the most powerful psychedelics known. Nearly all of the volunteers agreed it was among the most intense experiences of their lives. Many reported convincing encounters with intelligent nonhuman presences: angels, aliens, spirits. Strassman's detailed account is a riveting inquiring into the nature of the human mind and the therapeutic potential of psychedelics.