We are spirits housed in a body and, just as houses can be haunted, so can people. When the living succumb to dissociative states of consciousness, they become a magnet for lost, but clinging, spirits. Known as jinn, dybbuk, daemon, wuqabi or simply, the undead, they hover unseen on the earthly plane, ready to inhabit the most suitable body available. Documenting the life of wandering spirits and their impact on vulnerable human targets, Susan Martinez offers a radical departure from the standard psychological explanations for a host of pathological behaviour - including multiple personality, autism, epilepsy, migraines, obsessive compulsive disorder, depression, schizophrenia, anxiety, PTSD, self-destructive urges and strange outbursts - and reveals that hallucinations are often true impressions of spirit input. Martinez explains how mental health comes down to the delicate balance between self-control and spirit-control. When trauma triggers an escape response, the soul takes flight, leaving the mind susceptible to possession by discarnate entities. However, the spirit world can, also, bestow gifts upon those whose psyches are open, such as in the case of mediums, shamans, people who communicate with angels and many of the world's creative geniuses. Martinez presents “overshadowing” by spirits as a universal, cross-cultural phenomenon, documenting modern and traditional accounts as well as corroborating indigenous beliefs. She examines soul decay, soul travel both before and after death, as well as how knowledge of the spirit world can offer positive treatments for disorders like schizophrenia and autism. Providing a detailed guide to the spirit world and its inhabitants, the author offers checklists of symptoms of “overshadowing,” methods from the world's top exorcists and instructions on how to free spirits so they can continue their journey into the beyond,-,all the tools necessary to forearm us against soul snatchers and other enemies of the Light.