William Peter Blatty is a writer and American scenario writer , born with New York the January 7th 1928. Initially university, then journalist, Blatty devoted himself to the literature and the cinema. The major work in 1971 which revealed it with the general public is the Exorcist (appeared in France with the Éditions Robert Laffont) and put at the screen by the film of William Friedkin two years afterwards.

This book tells the history of the démoniaque case of possession and the Exorcisme which follows of the girl of an actress of television in the suburbs of Washington. It is based on actual facts: indeed, whereas William Peter Blatty is not yet that student it falls on an article reporting a case from exorcism on a boy 14 years, fore-mentioned Robby, in 1949 in the Maryland. Blatty is then put to write on the subject. The book is sold to 13 million specimens only in the United States.