David Jacobs came to UFO research as a historian, not a believer. His doctoral dissertation at the University of Wisconsin was a social history of the UFO controversy in the United States — an academic study of how American culture had processed an inexplicable phenomenon. He was a scholar of the debate, not a participant in it. That changed when he began conducting hypnotic regression sessions with abduction experiencers in the 1980s and could not stop thinking about what he was hearing.

Over more than three decades, Jacobs conducted hundreds of hypnotic regression sessions with more than 150 individuals. The pattern that emerged across these independently gathered accounts was, he came to believe, deeply disturbing: not random encounters with curious visitors, but a systematic process involving the harvesting of human biological material, the creation of hybrid beings combining human and non-human genetics, and a long-term program whose ultimate purpose remained unclear but whose consistency across witnesses suggested intentional design.

Secret Life (1992) documented his methodology and early findings. The Threat (1998) presented his most unsettling conclusions: that the abduction phenomenon is not benign, that the entities involved are not operating out of curiosity or benevolence, and that the integration of hybrid beings into human society may be an intended outcome of a program that has been running for decades. These are extraordinary claims. Jacobs acknowledges that they are supported only by hypnotic testimony, which is contested as an evidentiary standard. He insists, nonetheless, that the consistency of the accounts across hundreds of independent witnesses demands an explanation that mainstream science has not yet provided.