Snyder provides the rationale for why he created a new book on screenwriting and how his book differs from the many existing books on the subject. He makes four main arguments. Firstly, other books hold movies in too much reverence and use academic language instead of the jargon and shorthand of studio executives and professional screenwriters. Secondly, he decries how-to screenwriting guides that were not written by people who have actually sold scripts. Thirdly, he has taught the method in his book to other screenwriters who went on to achieve success, thus proving its merits. Finally, he claims to tell the hard truth about the success rates of script-selling.

Snyder also describes his annoyance with some Hollywood films that fail to achieve box-office success because the screenwriters violated the rules of making a good movie. As evidence, Snyder explains the title of his book: Save the Cat refers to a scene early on in a film wherein the hero does something to indicate their goodness, thus making the audience like and care about them. He uses the Al Pacino movie Sea of Love as a good example, and Lara Croft 2 as an example of where it is missing.