What evidence is there that evil entities can possess human beings and force them to commit horrific murders?

Black magic murders, Satanic sex cults and demonic possession are the diabolical practices that grab the tabloid headlines and reinforce the myth that evil and an unhealthy obsession with the occult are to blame for our increasingly violent society. But is the truth even darker and more disturbing?

From tribal magic and shamanism, through the work of WB Yeats and Aleister Crowley, to black magic rituals and New Age Nihilists, The Dark History of the Occult asks whether 'Satanic forces' are simply the emergence of the dark side of human nature, or whether we really have something to fear - namely, evil?