Even the shortest animated film will still contain a beginning, an instigated middle action, and an ending climax. This can be thought of as a compressed but complete three-act structure. For instance, the first short act of the 42-second Alien Song establishes Blit sitting on a chair under a spotlight. The instigating incident is the music starting. The main action of Act Two is the performance. The climax is the falling object. And the short third act is the subsequent silence.

Remember that Act One grabs the audience's attention, while the memory of Act Three is what they ultimately take home from the experience. This is not to imply that a second act is less important than its siblings, but if you successfully hook your audience with your first act and you have a unique and captivating climax and resolution worked out, figuring out the necessary action and beats of Act Two is very often the easy part.

Messing around with Story Structure
Some clever filmmakers get away with severely altering and reassembling the basic three-act structure. Pulp Fiction and Go bounce around between different places and times telling multiple stories, each with their own individual (yet related) three-act structure. The Usual Suspects begins after the second act, and the pieces leading up to it are told in flashback. The trip to India episode of Seinfeld, as well as the feature film, Memento, actually turn formal structure completely upside down and tell their stories in reverse. These severe structure rearrangements are often difficult to accomplish in a very short film because such intricacies require a fair amount of time to develop and ultimately connect.

Sometimes plot points are delivered in small pieces, and the complete structure is not revealed until the very end. This structure is sometimes referred to as a slowly unraveling puzzle, in which the audience is given bits and pieces along the way, but the entire story doesn't come together completely until the final piece is supplied, usually at the very end. Then the viewer often needs to spend some time putting the pieces together in his head before completely understanding the plot he's just witnessed. Atom Egoyan's Exotica and David Lynch's Mulholland Drive fall into this category. This structure generally requires the extended length of a feature film or that of a longer short to be accomplished effectively.

The Hero's Journey
No discussion on narrative structure would be complete without addressing Joseph Campbell's theories on the subject, in which he argued that every great story follows at least some variation of a rather formulaic series of events he called the hero's journey. The beats of this journey have been rearranged and modified by many scholars since Campbell first introduced them in his 1949 book, The Hero with a Thousand Faces. Here is a generalized description of the journey.

• Act One. You are introduced to the seemingly unremarkable protagonist in his unremarkable home world. A call to adventure is given, and the protagonist initially refuses until a mentor appears to provide an appropriate dose of philosophy, motivation and perhaps some new weaponry or skills, whereupon the future hero begins his journey into a new and treacherous world.
• Act Two. Some early but significant conflicts are met, as well as a few new characters who either join or attempt to thwart the journey. The final destination is eventually reached, where the supreme obstacle or villain is conquered, the stolen gem is retrieved or the princess is rescued.
• Act Three. The travelers head home along a somewhat dangerous path with the bested villain often in hot pursuit. The hero (usually) makes it back to his home world, delivering the goods, experiencing some kind of physical or spiritual resurrection and restoring order and happiness as he becomes known as the master of two worlds.