A classic how-to manual, William Wallace Cook's Plotto is one writer's personal method, painstakingly diagrammed for the benefit of others. The theory itself may be simple -- "Purpose opposed by Obstacle yields Conflict" -- but Cook takes his "Plottoist" through hundreds of situations and scenarios, guiding the reader's hand as a dizzying array of purposes and obstacles come to a head. Cook's method is broken down into three stages: First, the master plot. This four-page chart distills the most basic plot points into a three-line sentence. Next, the conflict situation. Each master plot leads the reader to a list of circumstances, distributed among 20 different conflict groups (these range from "Love's Beginning" to "Personal Limitations" to "Transgression"). There are over 2,000 unique conflict situations in the book, and each is cross-referenced with designs for how the situation might have started, or where it might go.
Finally, there are character combinations -- Cook offers an extensive index of protagonists, each cross-referenced with various supporting players -- themselves tied to various conflict situations, for what appears to be an inexhaustible reservoir of suggestions and inspiration.