Summer movies are often described as formulaic. But what few people know is that there is actually a formula—one that lays out, on a page-by-page basis, exactly what should happen when in a screenplay. It’s as if a mad scientist has discovered a secret process for making a perfect, or at least perfectly conventional, summer blockbuster.

The formula didn’t come from a mad scientist. Instead it came from a screenplay guidebook

—Hollywood and Blake Snyder’s screenwriting book, Save the Cat! - Slate Magazine