Based partially on the 1952 book The Devils of Loudun by Aldous Huxley, and partially on the 1960 play The Devils by John Whiting, also based on Huxley's book. The film is a dramatised historical account of the rise and fall of Urbain Grandier, a 17th-century Roman Catholic priest executed for witchcraft following the supposed possessions in Loudun, France. Reed plays Grandier in the film and Vanessa Redgrave plays a sexually-repressed nun who finds herself inadvertently responsible for the accusations.
The film faced harsh reaction from national film rating systems due to its disturbingly violent, sexual, and religious content, and originally received an X rating in both Britain and the United States. It was banned in several countries, and eventually heavily edited for release in others. The film has never received a release in its original, uncut form in various countries, and is largely unavailable in the home video market.
So that is way I signed the petition to convence warner bros. to release an unrated version because when 100 film makers and critics were asked to cite what they considered to be the ten most important films ever made, The Devils featured in the lists submitted by critic Mark Kermode and director Alex Cox.