Exposition is fickle. It’s one of the few tools of storytelling the average filmgoer is familiar enough with to spot – and ridicule – from a mile away. No one likes to see the pieces of the film they’re about to watch be put into place, they want to feel that they’ve just entered a world in medias res. Still, it’s an unavoidable element of screenwriting, so how do you know how much is enough, or, more importantly, too much at once?
Well, most exposition is cornered off in the opening act, preceding the inciting incident that sets the story proper into motion. So every minute before the terrorists invade Nakatomi Plaza in Die Hard is devoted to
exposition, however cleverly disguised. You learn who all the key players are, their dynamics, and what the primary location and nature of the scenario is. Further exposition, which is not immediately important
for the story to go into motion, such as Sergeant Al Powell’s past failure, is doled out only when absolutely necessary, giving space for the information to settle long enough for the pay-off to feel earned. That said, the majority of exposition remains at the start of the film, but how much should be corralled into Act One?
Conveniently most audience members, and therefore most writers, have an internal barometer for these things. Take nearly any ultra-popular classic movie, and spot where the exposition ends and the key events start taking place. Practically without fail, this point will come at about 20 minutes into the running time. If you’re still setting up characters and dynamics 27-minutes in, watchers may become antsy. If you’ve stopped before that point, you’ve likely not given enough space for your audience to absorb your set-up.
Fantasy films typically have the most heavy-lifting to do when it comes to exposition, but the best of them hold fast to this unwritten rule. For the first Star Wars, Luke discovers Leia’s distress call, the message that gets him involved in the rebellion by searching for Obi-wan, 21 minutes into the film. For The Thief of Bagdad – one of the most purely entertaining of all fantasy adventures – the disenfranchised Prince and his new peasant friend Abu escape the prison of the evil Jaffar, and set out on their quest 19 minutes in. Even The Fellowship of the Ring, the Lord of the Rings film burdened with introducing audiences to one of the most richly complex fantasy worlds ever imagined, sees Frodo first pick up the One Ring 25 minutes into the film, after Bilbo leaves it behind at 23 minutes.
The Matrix, The African Queen, Stagecoach, Lawrence of Arabia, Jaws it may be simpler to list exceptions to this particular rule. If you’re keen on playing to the sensibilities of an audience, eager for a conventionally paced and swiftly moving piece of entertainment, focusing your exposition into the first twenty minutes of your film, and then immediately launching into the meat of the plot is a valuable way to begin putting everything in its right place.