Although sprawling in prose, The Exorcist is a surprisingly tight novel, with relatively few characters. It begins with, and stays centered on, the MacNeil household. The mother, Chris, is an actress, based by Blatty on his friend and onetime neighbor Shirley MacLaine. (After the phenomenal social reaction to the novel, Blatty regretted this, since some people assumed Shirley MacLaine actually had a daughter who had been possessed.)

Despite Chris's career, Blatty eschewed the genre conventions of show-business novels; Chris is down to earth, not sexually active, and—other than an actress —primarily a concerned mother. One subplot, cut in the movie, shows Chris forgoing a much-desired opportunity to direct, due to the need to care for her daughter. That daughter, Regan, is not as fully developed, because her personality is too soon eclipsed by the possession. Still, she is, like her mother, sunny but capable of...