My wife and I watched the movie Limitless the other night. In general we liked it (she more than I), but there was one aspect of the storytelling that annoyed us both. (Not having read the novel, The Dark Fields, on which the movie is based, I don't know if the problem began in the novel or is an artifact of the shorthand scriptwriters must use when transferring a novel to film.)
If you haven't seen the film and don't like spoilers, skip this paragraph. Limitless is the tale of a loser would-be writer named Morro in denial about his addictions and self-sabotaging behaviors. We see Morro dodging creditors, avoiding his editor (he's months behind on delivering a novel he's been paid for), being dumped by his successful girlfriend — who's just been promoted to editor — and rambling incoherently to strangers about the book he intends to write someday. By chance he bumps into his ex-wife's brother, Vernon, who used to be his coke supplier. The two pick up where they left off, only now the drug is NZT, a mind enhancer developed by a major pharmaceutical company that gives it's user access to all of his brain's potential. One tab and loser Morro writes a thesis for a beautiful law student (for which she is physically grateful), cleans his apartment, and writes four chapters of the novel in an hour. The next morning he's back to normal and goes in search of Vernon. Vernon will keep Morro supplied if Morro works for him. He sends Morro out on errands. When Morro returns, Vernon is dead and his apartment has been trashed. Because he knows Vernon, Morro is able to find what the killers couldn't—where the supply of NZT and Vernon's client list are hidden. For the next hour we watch Morro manifesting a wide range of talents as he shoots to the top as an investor and the editor-girlfriend who dumped him takes him back. In the process Morro make three fundamental mistakes: he borrows needed seed money from a Russian loan shark; he doesn't hire a biochemist to try and replicate NZT until his supply is half gone; and he attracts the attention of Robert DeNiro (who in this case is the guy who hires Donald Trump to polish his shoes). The Russian threatens Morro in a Russian/Welsh accent until he gets some NZT; the scientis tells him it will take six to twelve months to synthesize NZT; DeNiro hires him and watches him very closely. Then Morro learns all of Vernon's other customers are either dead or in comas; quitting NZT has lethal side effects. His girlfriend learns of NZT and dumps him again—she's not interested in a guy who can only get ahead on drugs. Then things get worse. Much bloodshed ensues, with a fairly believable outcome. Then.... In the last several minutes (from when the words "One year later" appear on the screen until the end) everything is wrapped up at warp speed. Every problem threatening the hero is not only solved, but presented as already having been solved. The film ends with Morro and his girlfriend at a Chinese restaurant (he banters with the waiter in Mandarin).
In hashing through the movie after the fact, Valerie and I were able to spot moments in the film — bits of dialog, visual clues — that made all the loose ends getting tied in a bow plausible. So in a sense the ending didn't just pop out of thin air. But. We should not have had to work that hard to convince ourselves the resolution made sense.
I first heard of Chekhov's Gun from my theatre professor at Rollins College forty years ago. Dr. Juergens quoted Anton Chekhov's maxim as: "If there's a rifle on stage in act one, someone must be shot in act two." Though I've since learned that's a paraphrase, it's still the version I prefer; who knows, perhaps Chekhov did say that at one time. What we do know is that he wrote two different versions in two letters to colleagues: "If in the first act you have hung a pistol on the wall, then in the following one it should be fired. Otherwise don't put it there." and "One must not put a rifle on the stage if no one is thinking of firing it."
Chekhov's example is particularly literal — he certainly knew there were reasons other than shooting for a gun to be on stage. If the protagonist is a pacifist vegan, a display of rifles and mounted animal heads dominating the living room of his employer or potential father-in-law could set up a conflict. Chekhov's point was that nothing should be on stage — or in the story — that does not serve a purpose.
However, it can be taken another way; and very often is. Chekhov's Gun can also be used to illustrate the necessity of foreshadowing (and that's the sense I was addressing in my comments on Limitless). A writer who pulls a resolution or character or motivation or event out of thin air is not playing fair with her readers. Okay, everything in our stories comes out of thin air—or whatever it is we have between our ears; point taken. By 'thin air' I mean anything outside the scope of the story.
This rule is most often cited in mystery fiction — a well-told mystery presents the reader with all the information necessary to solve whatever puzzle confronts the protagonist in such a way that the reader has an of course! experience at the dénouement (but not so obviously that the reader solves the problem before the protagonist). In a classic Christie example, Poirot asks the butler to tell him the date on the victim's desk calendar. That worthy leans over to peer at the page before saying "the fourth." The important information is not that the victim was last at his desk on the fourth, but that the butler is very nearsighted; his eyewitness account is unreliable. Ellery Queen used to take this a step farther. He (okay, 'they') would break the fourth wall of the story to challenge the reader: "You now have all the clues you need to solve the mystery. Do you know who the killer is?" (I know I was not the only reader to stop at that point and go back over the story to determine what information was relevant and solve the case before Ellery.)
However, this fundamental of writing is not restricted to mysteries. All writers owe the reader a story that makes sense, if only internally. The warrior can't suddenly remember an eldritch chant learned in youth to best the dark mage with no previous mention of her childhood. The medical missionary being forced to abandon a vital clinic due to lack of funds can't have a rich aunt die and leave him enough money to run the clinic for decades. A protagonist cannot be prevented from marrying her soul mate by religious/moral/ethical/political restraints for 342 pages only to have everyone agree on page 343 that love conquers—or perhaps trumps—all and they should live happily ever.
There must be scenes early on of the child-who-would-be-warrior learning the chants — perhaps as preparation for life she chose not to follow; perhaps as singing along with what she thought were nonsense songs her father had made up to entertain her. The doctor's family, and his relationship to them, must be established early on. (Perhaps his parents were angry/disappointed in him for "wasting" his talents on the poor when he should be trying to find a cure for his aunt's cancer — or at least taking care of her — while he had the hope his aunt, who had been a pioneer in her day, secretly approved of his chosen work, even if she never said it in so many words.) Two people, no matter how in love, cannot violate the fundamental tenets of their respective worlds unless all the groundwork for their reasons and actions that makes sense within the context of the story has been set in place from the beginning.
And none of these things can be done with a glib throwaway line here or a heretofore unmentioned letter there or a character wandering randomly in from the wings at precisely the right moment. Serendipity happens in real life; it has no place in fiction.
Propping Chekhov's Gun in the corner of the set before the curtain rises is not sufficient. It has to be carried on stage in the full glare of the lights, then loaded and placed in position in plain sight of the audience. It's not necessary to shout or call attention to the process, but every step must be clear and happen in order. Anything less is cheating the reader. You can't fire the gun in act two unless you cock it in act one.