The Hollywood animation studio Pixar is home to some of the most successful mass-market storytellers of our age. ‘Story artist’ Austin Madison, who’s worked on blockbusters including Ratatouille, Wall-E and Up, has shared a structure he says all Pixar films must adhere to. The action starts with a protagonist who has a goal, living in a settled world. Then a challenge comes that forces them into a cause-and-effect sequence of events that eventually builds to a climax that demonstrates the triumph of good over evil and the revelation of the story’s moral.