Psychiatrist John Mack discusses clinical case histories involving memories of alien encounters. He suggests that these cases transcend dualistic categories, such as reality/fantasy, physical/mental, true/false. He argues that UFO abductions differ from past-life memories, near-death experiences and satanic ritual abuse because of the presence of corroborating physical evidence.

The late John Mack, M.D., a professor of psychiatry at Harvard, received a Pulitzer Prize for his biography of T. E. Lawrence and is author of Abduction: Human Encounters with Aliens.