John Deacon uses hypnosis to research altered states of consciousness. One of his subjects, Michael Peacocke, is unusually susceptible and in their first session together he recalls a Close Encounter which took place some years before. Deacon is sceptical of UFOs and dismisses Peacocke's story as an adolescent sexual fantasy. But then inexplicable things happen - the tape of the session is mysteriously erased, Deacon's dog is killed, he and Michael see a pterodactyl, Michael's girlfriend is menaced by Men in Black - and Deacon is forced to reconsider. Could UFOs be symbols projected from the collective unconscious? Are they messages from the biomatrix? Does the mind have the ability to project tulpas, objects and people which are physically real yet somehow illusory?