On December 26, 1973, The Exorcist was released. Within days it had become legend. Moviegoers braved hours-long lines in winter weather to see it. Some audience members famously fainted or vomited. Half a century later, the movie that both inspired and transcends the modern horror genre has lost none of its power to terrify and unsettle.

The Exorcist Legacy reveals the complete story of this cultural phenomenon, from the real-life exorcism in 1949 Maryland that inspired William Peter Blatty's bestselling novel on which the movie is based, to its many sequels, prequels, TV series, and homages. Nat Segaloff, biographer of the film's director, William Friedkin, draws on original interviews with cast, crew, and participants as well as revelations from personal papers to present an intriguing and surprising new view of the making of movie, and its aftermath.

Segaloff also examines as never before the keys to the movie's enduring appeal. Friedkin and Blatty's goal was far more ambitious than making a scary movie; they aimed to make people "think about the concept of good and evil." The Exorcist succeeds, and then some, not just by creating on-screen scares, but by challenging viewers' deepest personal beliefs—and fears.