There are three kinds of foreshadowing. There’s covert foreshadowing, where the shadow doesn’t appear clearly until the light of past events illuminates the hidden clues. There’s overt foreshadowing, which streams before the event, giving hints but veiling the true shape of what will occur. Then there’s event foreshadowing, spreading the scenario like multiple faint shadows from the vashta nerada in Doctor Who.

Foreshadowing is, put simply, a warning or indication of a future event. 

1.  Covert Foreshadowing

Covert foreshadowing happens when the possibility of an event is hinted at enough that the result doesn’t feel like a sudden shift in the story. If an aunt is going to turn out to be an undercover agent in the climax of a story, brief mentions of her skills or quirks throughout the book is a great way to foreshadow her reveal. Readers probably won’t realize the meaning of the clues until they’ve reached the end, but once they know the truth they will wonder how they didn’t figure it out.

Many things can foreshadow an eventual twist: from jokes, to dreams, to declaring something impossible, to a quirky character trait. Of course you don’t want readers to perceive the twist beforehand, so be careful how much foreshadowing you include. Just a little bit spices up the story. The characters themselves can contemplate the foreshadowed clues as well, perhaps even alluding to the coming twist in a half-correct manner before dismissing it as false.

Also, in covert foreshadowing, a writer can throw in red herrings—giving the illusion that the climax will go in one direction when it will actually go in another. This can be fun, but you must be careful so that readers don’t feel cheated. The red herring events should have a valid reason, and another layer of foreshadowing will be needed for the real event.

2.  Overt Foreshadowing

Overt foreshadowing is a good tool to build suspense, although it should be used sparingly. It openly hints at an impending trial or problem, casting a clear shadow before the event and baiting readers with just enough information to keep them devouring the story. Overt foreshadowing normally shows up in thoughts or single lines: We‘d meet on the morrow. Or so we thought. No one guessed the terror that was coming. It can also come in the form of gradually revealed dreams or flashbacks that demonstrate the reason for a situation or characters actions, which then affects the rest of the story.

A few touches of overt foreshadowing will add mystery and suspense as the action builds, charging your story with tension during preparation scenes. Overt foreshadowing is not a cure for slow or boring writing, however, and you must fulfill the expectations it will instill in your readers’ minds.

The choice between using covert or overt foreshadowing (or a mix of the two) is up to you and will depend on your book’s style and the type of twist you are writing. Do you want your readers gritting their teeth in anticipation because they’re aware something will happen but can’t determine what, or do you want them to sit stunned, unable to believe what they just read—and that they didn’t foresee it?

3.  Event Foreshadowing

Event foreshadowing is when scenes are crafted to mirror a climatic situation. For instance, memories of a parent’s death end up being similar to the situation the main character is thrust into. Can he get out alive or will he fail and die like his parent? Or perhaps a climactic scene is pre-played with different characters—like in Hamilton, where the final duel scene is foreshadowed in the musical’s two preceding duels. By the climax, the audience already knows the setting and potential results. Event foreshadowing unifies the story, connecting important events with a thread of familiarity, while also displaying various facets or repercussions of a theme/situation.

Purposeful Foreshadowing

For every twist in a story, there ought to be a foreshadowing line or event. Depending on the type or mixture of types that you use, foreshadowing will shape readers’ expectations. If they are given numerous hints about the mystery surrounding an old uncle, they’re going to be disappointed if he was only trying to carve a surprise gift for his niece when they were expecting him to be a secret agent or villain in disguise. Foreshadowing draws readers along, and it must deliver.

Foreshadowing (especially covert and event) is necessary to make plot twists realistic. If a long lost prince suddenly appears to lead the army, with no mention of the legends, his mysterious past, or rumors of his survival, it’s going to be too abrupt, too easy. But if the same event is properly built toward (even if the characters don’t believe the prince can still be alive), readers will accept the possibility of his return and won’t be as shocked.

Foreshadowing involves planning, but it’s thrilling both as a reader and a writer.

Although the process can be complicated at times, as writers we get to weave truth and subtle “slight of word” to hide the reality in broad daylight or keep it so tightly sealed that readers are begging to find out more. As readers, we get to try deciphering events that might be more than they seem and guess at what will unfold as the story progresses. Spend the time needed to perfect the foreshadowing in your story until it runs smoothly. You won’t regret it.