Fail Safe is a 1964 Cold War thriller film directed by Sidney Lumet, based on the 1962 novel of the same name by Eugene Burdick and Harvey Wheeler. It portrays a fictional account of a nuclear crisis. The film features performances by actors Henry Fonda, Dan O'Herlihy, Walter Matthau and Frank Overton. Larry Hagman, Fritz Weaver, Dom DeLuise and Sorrell Booke appeared in early film roles.
The movie Fail Safe was made two years after the novel was written.
the book was released in 1962 and the movie came out in 1964. That's a two year difference.