(Spoilers: Sixth Sense, Fight Club, The Usual Suspects, The Empire Strikes Back, The Crying Game, Citizen Kane - in other words, the biggest spoilers of all time!)
A great twist ending, the kind at the end of Fight Club (screenplay by Jim Uhls) or The Sixth Sense (written by M. Night Shyamalan) that completely redefines everything that’s come before, is a powerful thing. When done well, as in these examples, it can take a film from good to legendary. But these kinds of endings are few and far between. Let’s look at how great twist endings work.
The first rule is that the story must be good without the twist. You cannot expect an audience to watch 90 or 100 minutes of film before they get to the good stuff. This means that the twist can’t actually be crucial to the concept. The twist may be the most memorable thing in the film, but the story concept must stand on its own.
For example, Fight Club is about a miserably unhappy man, a self-described slave to consumerism, who falls under the sway of a charismatic new friend. The two form a fight club to get in touch with their primitive side, but things spiral out of control when the club members resort to vandalism and terrorism to bring down consumer society.
The fact that the unhappy man and his friend turn out to be the same person is a critical revelation about the main character, but not critical to get us interested and involved in the story. The drama and conflict come from the unhappy man's transformation due to physical brutality, and then from the fight club spinning out of control – not the twist, though that does add additional conflict and drama for act three. You could use the above log line to craft a very interesting story that didn’t have a twist ending at all.
Similarly, the story of The Sixth Sense is about Malcolm attempting to help Cole overcome his problem. The conflict in the story comes from Cole’s unique ability to see ghosts and how that terrorizes him; the stakes relate to Cole’s happiness and sanity. For Malcolm, the stakes are redemption for his failure to help a previous, similarly afflicted patient. The twist, that Malcolm is actually a ghost that needs Cole’s help, relates to the subplot of Malcolm and his strained relationship with his wife Anna. It actually has little impact on the main plot line!
A perfectly good movie might have been made about a living psychologist trying to help a child who sees ghosts. In fact, Shyamalan has said that Malcolm was alive in the first several drafts of his script. It wasn’t until fairly late in the process that he hit upon the idea that Malcolm was actually a ghost as well.
Which suggests two important elements of twist endings:
First, they must grow organically out of the story concept. When you try to force a twist (as Shyamalan has a few times since), the story will feel labored or convoluted or unsatisfying. In the worst cases, the screenplay is boring until the twist is revealed. Only once we know what was really going on do the previous events become interesting. But this doesn’t work – it’s too late. The audience has already checked out. Industry readers will have stopped reading long before discovering the twist.
The second factor is that the twists usually have more to do with the character's arc than with the plot. Consider the big reveal at the end of The Empire Strikes Back (story by George Lucas, screenplay by Leigh Brackett and Lawrence Kasdan). Learning that Darth Vader is Luke's father doesn't affect the outcome of the plot, but it is devastating to Luke and his beliefs.
Similarly, Fergus learning that Dil is actually a man in The Crying Game (written by Neil Jordan) – which happened more in the middle of the movie than the end, but still redefined everything we thought we knew – has a huge impact on Fergus emotionally, but doesn't materially change any of the events in the plot. If Dil had actually been a woman, everything would have come out exactly the same way. Yet that twist catapulted the small film into movie legend.
Another movie with a legendary reveal at the end is The Usual Suspects (written by Christopher McQuarrie), but this is actually a different animal than the twists in the movies I’ve discussed so far. In Fight Club, The Sixth Sense, etc. the twists are shocking at least partly because they are unexpected. But The Usual Suspects is a mystery – a question is raised (Who is Kaiser Sose?) and we know there must be an answer. It’s just that the answer is particularly shocking.
This is also true of Citizen Kane (screenplay by Herman J. Mankiewicz and Orson Welles). The reporter is trying to find out the meaning of "Rosebud." The revelation of what Rosebud was at the end is surprising, but not truly a twist.
Whether using the mystery format or attempting an unexpected twist, the need to use planting and red herrings is equally critical. When the twist appears it must be plausible and understandable, which means it must be set up. But of course the audience must not anticipate it or you lose the surprise.
You have to think like a magician – distract the audience from the clue. Look at the scene where Malcolm goes to have dinner with Anna in The Sixth Sense. In retrospect, she never actually spoke to him or acknowledged his presence. Yet we don’t notice in the scene because the scene is given another reason for existing – Malcolm is late, thinks Anna is angry with him and apologizes. The scene is about their relationship. That’s what we pay attention to and why we don’t notice or question that she doesn’t talk directly to him.
This is perhaps why it’s so important the story works without the twist. In a way, the entire plots of The Sixth Sense and Fight Club and The Crying Game function as red herrings, distracting us from the coming revelation.
Remember, most great movies do not have the kind of twists that redefine all of the previous events. It is absolutely not necessary for a successful film. And if you are going to attempt a big twist, first make sure your story is good without it.