Harpur's starting-point is that vast numbers of ordinary, reliable people, with no track record of involvement in Otherworldly phenomena, who would be regarded as reliable witnesses in all other circumstances, persist in reporting vivid encounters with the denizens of the otherworld. Those encounters in our age are likely to be with alleged aliens, large or small, but bear uncanny resemblances to the age-old encounters with faerie folk, spirits, and other manifestations of different places and other times.... The standard response to all this is to argue either that it is all in us, in the form of persistent patterns of hallucination or madness; or the projection of archetypal patterns onto reality. Alternatively, the phenomena are taken seriously as being evidence of something really out there in the physical world, as aliens visiting the Earth, or prehistoric creatures living in deep cold lakes etc. Harpur pursues a different, and more challenging line. What is at stake, he suggests, is the nature of reality itself.