When the storyteller describes a gun hanging over the mantlepiece, we assume it’s there for a reason. This detail primes the audience, creating expectation, tension and suspense. It acts as a ‘red flag’, a ‘lit lantern’ alerting us to the likelihood that it will be used later. This is the principle of ‘Checkov’s gun’: irrelevant details are purged, and pertinent plot details retained.
The technique of suggesting story elements to an audience is called foreshadowing. It serves a number of purposes, from setting the scene about what might happen later, to creating resonance. In Romeo and Juliet Benvolio describes Romeo’s love for Rosaline as ‘rank poison’, foreshadowing Romeo’s death by swallowing poison. Foreshadowing functions on a basic technical level as well, by creating a more believable story. When, for example, a character pulls a gun ‘out of nowhere’, it’s unbelievable, but with a hint of foreshadowing (mentioning a gun on the wall) it seems more natural. Believability plays an important part in keeping the audience involved in the story.
Stories are crafted from sequences of action and reaction, assembled together to create realistic narratives, in spite of their artifice. They highlight changes of fortune in the characters we care about (and their enemies), provoking empathy for the protagonist when they face tragedy, and joy when they succeed. Foreshadowing provides audience entertainment on another level: the conversation the audience has with the writer when they attempt to predict where the story is going.
Foreshadowing can occur in different ways: a precursor event (which may occur on a smaller scale and gradually increase), when a character makes a prophesy about the future, and when the event is foreshadowed by anxiety and fear, of an individual, or at a group level. A common storytelling device is the inclusion of an eccentric character, often a misfit, a man or woman who prophetically sees disaster, and is dismissed as crazy.
Another device is the disturbing nightmare, a warning sign that something disastrous will happen, or for a character to experience memories, as flashbacks, which are significant to the his or her outcome. In The Thin Red Line (1998), the audience experiences a soldier’s memories, which explains his backstory, a sensitive human being in a violent and merciless war — but it also works as his life flashing before him at the moment of his death, which is revealed later in the story (along with the recurring motif of light pouring through the jungle canopy like a backlit cathedral window, setting the tone for the story, its spirituality, and his own mortality).
These warnings can be expressed through the protagonist and his opponent, or through the environment around them. Character’s often exhibit signs of trouble when they lose their cool and inadvertently reveal their plan to their enemy, or when they become irrational and make ego-based decisions, instead of rational ones. In The Matrix (1999) the central character notices strange things happening in his world around him that he cannot explain. These are the ‘glitches’ in the Matrix, which provoke him into questioning reality. In disaster films foreshadowing often occurs when one character arrogantly states that the disaster, which we are about to witness, could never happen.
Sometimes a character’s personality is enough for us to figure out what will happen. In the Second World War film Attack (1956) an officer’s incompetence, and inability to think calmly under pressure, leads to men needlessly dying under his command. In The Thin Red Line (1998) an officer who is sensible and paternal, and is able to stay rational under duress, saves his men from pointless slaughter. The warning signs usually increase on a scale as the stakes also rise. In the The Poseidon Adventure (1972) carelessness and arrogance lead to a passenger ship capsizing. In The Towing Inferno (1974) an inability to take a small fire seriously, combined with safely reductions to save money, places all the occupants of a skyscraper in danger.
Foreshadowing creates tension and suspense, it helps to make stories more realistic. Sometimes it works almost subliminally, in the background — through the music, the weather, or through the location — resonating with implication.