Like all stories, mysteries are told by narrators. Even mysteries told in the third person have a narrator, though the story is told by an omniscient narrator with a kind of ‘bird’s eye view’ of the story and its characters. But if you are reading a mystery written in the first person, the ‘I’ of the story is your narrator, and in this very intimate world of the first-person narrator, you as a reader need to be on your guard because the main mission in the life of the first-person narrator is to pull the wool over your eyes!
This is very often how the author introduces red herrings. You as the reader get drawn into the world of the first-person narrator, he or she seems nice, or maybe they are really horrid, but either way, they unfold to you the plot of the story as they see it and it all seems very plausible and it is only at the end you realise that they missed out crucial information or disguised themselves or presented events in a rather biased manner, with the intention of thwarting your attempt to solve the mystery yourself.
Maybe they are seeking to divert suspicion from themselves, or even if you know what they did and how they did it, it is important for the first-person narrator that you sympathise, even condone what they did. They deceive you with half-truths, half-lies or even simply accidental misinterpretation. The bumbling narrator is in many ways the worst. They disarm you with their apparent incompetence, they admit to being forgetful, or unsure of their facts, and all the time—all the time—they are deliberately drawing you into their web.
They might throw you off the scent by seeming to reveal some great truth; they admit to some minor sin in order to distract you from your hunt for clues. Their very openness, the revelation of their intimate thoughts, feelings and actions actually conceals greater guilt—the guilt of deception. Even worse, the author actually uses them to control your reaction to the story and how information is revealed to you. Often in an apparent display of ‘fairness’ they will actually allow the narrator’s flaw to be revealed early on in the story, in the hope that you will have forgotten it by the time the story reaches its denouement. The author manipulates your sympathy, forcing you to acquit the narrator of wrong-doing as you stand in the place of the judge and jury of the action of the story.
Now that you know this, you are forearmed, and will be on the lookout for these artful devices!
A few noted novels with unreliable narrators:
Agatha Christie’s infamous The Murder of Roger Ackroyd
Bret Easton Ellis’s American Psycho
Margaret Atwood’s The Blind Assassin
Gillian Flynn’s Gone Girl
Vladimir Nabokov’s Lolita
Ian McEwan’s Atonement