The Ninth Configuration

The Ninth Configuration, (also known as Twinkle, Twinkle, "Killer" Kane) is a 1980 American film directed by William Peter Blatty. The film is based on Blatty's novel, The Ninth Configuration (1978) which was itself a reworking of an earlier version of the novel, first published in 1966 as Twinkle, Twinkle, "Killer" Kane! The initial 1966 publication of the novel featured an exclamation mark at the end of the title, while all subsequent publications saw it removed.

The first half of the film has the predominant tone and style of a comic farce. In the second half, the film becomes darker as it delves deeper into its central issues of human suffering, sacrifice and faith. The film also frequently blurs the line between the sane and the insane.