Rogo presents a history via accounts of the lives and work of those who researched the spiritistic theory of mental illness as well as of those who investigate it today. According to the spiritistic theory, some cases of psychological disorder and multiple personality may be the end result of obsession or even possession by discarnate spirits. Part 1 reviews the following cases researched by James H. Hyslop: the Thompson-Gifford case, Etta de Camp, and the Doris Fischer case. In Part 2 there is a chapter which reviews the research work of Titus Bull and Carl Wickland in which, working through a medium or a spiritualist rescue circle, obsessing or possessing spirits were contacted and attempts were made to convince them to progress spiritually and to let go their hold on the living. The next chapter describes the work of Walter Franklin Prince’s efforts to exorcise the possessed. Another chapter concerns the ministry of Elwood Worcester. The third part deals with research work today, and has chapters on Kardecismo groups (Brazilian spiritistic followers of Allan Kardec) and the modern channel Matthew Bronson who is involved with a rescue circle in Northern California. There is a chapter on M. Scott Peck, who holds that some multiple personality cases are a form of demonic possession. Peck has developed a method of exorcism to deal with them. Also touched on is the work of Ralph Allison. In the next chapter Rogo considers whether or not cases of apparent possession are literally true: that is, with the questions “Do we ultimately survive death,” and “Can we subsequently reach back and contact the living?” He considers the possibilities of fraud and the super-ESP hypothesis, and concludes that at least some cases of genuine spirit possession probably exist.